diff --git a/play.py b/play.py
index 9f687f3..d0cc8a8 100644
--- a/play.py
+++ b/play.py
@@ -4,22 +4,3 @@ import scgenerator as sc
 import matplotlib.pyplot as plt
 from pathlib import Path
 from pprint import pprint
-
-
-def _main():
-    print(os.getcwd())
-    for v_list, params in sc.Configuration("PM1550+PM2000D+PM1550/Pos30000.toml"):
-        print(params.fiber_map)
-
-
-def main():
-    drr = os.getcwd()
-    os.chdir("/Users/benoitsierro/Nextcloud/PhD/Supercontinuum/PCF Simulations")
-    try:
-        _main()
-    finally:
-        os.chdir(drr)
-
-
-if __name__ == "__main__":
-    main()
diff --git a/src/scgenerator/__init__.py b/src/scgenerator/__init__.py
index 997e495..6cb8fcb 100644
--- a/src/scgenerator/__init__.py
+++ b/src/scgenerator/__init__.py
@@ -1,9 +1,10 @@
-from . import math, utils
+from . import math
 from .math import abs2, argclosest, span
 from .physics import fiber, materials, pulse, simulate, units
 from .physics.simulate import RK4IP, parallel_RK4IP, run_simulation
 from .plotting import mean_values_plot, plot_spectrogram, propagation_plot, single_position_plot
 from .spectra import Pulse, Spectrum
-from .utils import Paths, open_config, parameter
-from .utils.parameter import Configuration, Parameters
-from .utils.utils import PlotRange
+from ._utils import Paths, open_config, parameter
+from ._utils.parameter import Configuration, Parameters
+from ._utils.utils import PlotRange
+from ._utils.variationer import Variationer, VariationDescriptor, VariationSpecsError
diff --git a/src/scgenerator/utils/__init__.py b/src/scgenerator/_utils/__init__.py
similarity index 98%
rename from src/scgenerator/utils/__init__.py
rename to src/scgenerator/_utils/__init__.py
index fdcbcea..03c8859 100644
--- a/src/scgenerator/utils/__init__.py
+++ b/src/scgenerator/_utils/__init__.py
@@ -25,7 +25,7 @@ import pkg_resources as pkg
 import toml
 from tqdm import tqdm
 
-from ..const import PARAM_FN, PARAM_SEPARATOR, SPEC1_FN, SPECN_FN, Z_FN, __version__
+from ..const import PARAM_FN, PARAM_SEPARATOR, SPEC1_FN, SPECN_FN1, Z_FN, __version__
 from ..env import pbar_policy
 from ..logger import get_logger
 
@@ -143,7 +143,8 @@ def resolve_loadfile_arg(dico: dict[str, Any]) -> dict[str, Any]:
     return dico
 
 
-def load_toml(descr: str) -> dict[str, Any]:
+def load_toml(descr: os.PathLike) -> dict[str, Any]:
+    descr = str(descr)
     if ":" in descr:
         path, entry = descr.split(":", 1)
         with open(path) as file:
@@ -188,6 +189,7 @@ def load_config_sequence(path: os.PathLike) -> tuple[Path, list[dict[str, Any]]]
         params.setdefault("variable", {})
         configs.append(loaded_config | params)
     configs[0]["variable"] = loaded_config.get("variable", {}) | configs[0]["variable"]
+    configs[0]["variable"]["num"] = list(range(configs[0].get("repeat", 1)))
 
     return Path(final_path), configs
 
@@ -341,7 +343,7 @@ def merge_path_tree(
 
     for i, (z, merged_spectra) in enumerate(merge_spectra(path_tree)):
         z_arr.append(z)
-        spec_out_name = SPECN_FN.format(i)
+        spec_out_name = SPECN_FN1.format(i)
         np.save(destination / spec_out_name, merged_spectra)
         if z_callback is not None:
             z_callback(i)
diff --git a/src/scgenerator/utils/cache.py b/src/scgenerator/_utils/cache.py
similarity index 100%
rename from src/scgenerator/utils/cache.py
rename to src/scgenerator/_utils/cache.py
diff --git a/src/scgenerator/utils/parameter.py b/src/scgenerator/_utils/parameter.py
similarity index 94%
rename from src/scgenerator/utils/parameter.py
rename to src/scgenerator/_utils/parameter.py
index fa43c58..f7d7c1a 100644
--- a/src/scgenerator/utils/parameter.py
+++ b/src/scgenerator/_utils/parameter.py
@@ -14,14 +14,15 @@ from typing import Any, Callable, Generator, Iterable, Literal, Optional, Sequen
 
 import numpy as np
 from numpy.lib import isin
-from scgenerator.utils import ensure_folder, variationer
 
-from .. import math, utils
+from .. import math
 from ..const import PARAM_FN, PARAM_SEPARATOR, __version__
 from ..errors import EvaluatorError, NoDefaultError
 from ..logger import get_logger
 from ..physics import fiber, materials, pulse, units
-from ..utils.variationer import VariationDescriptor, Variationer
+from .._utils.variationer import VariationDescriptor, Variationer
+from .. import _utils as utils
+from .. import env
 from .utils import func_rewrite, _mock_function, get_arg_names
 
 T = TypeVar("T")
@@ -312,13 +313,6 @@ class Parameter:
             return f"{num_str} {unit}"
 
 
-def fiber_map_converter(d: dict[str, str]) -> list[tuple[float, str]]:
-    if isinstance(d, dict):
-        return [(float(k), v) for k, v in d.items()]
-    else:
-        return [(float(k), v) for k, v in d]
-
-
 @dataclass
 class Parameters:
     """
@@ -432,15 +426,13 @@ class Parameters:
     const_qty: np.ndarray = Parameter(type_checker(np.ndarray))
     beta_func: Callable[[float], list[float]] = Parameter(func_validator)
     gamma_func: Callable[[float], float] = Parameter(func_validator)
-    fiber_map: list[tuple[float, str]] = Parameter(
-        validator_list(type_checker(tuple)), converter=fiber_map_converter
-    )
+
+    num: int = Parameter(non_negative(int))
     datetime: datetime_module.datetime = Parameter(type_checker(datetime_module.datetime))
     version: str = Parameter(string)
 
     def prepare_for_dump(self) -> dict[str, Any]:
         param = asdict(self)
-        param["fiber_map"] = [(str(z), n) for z, n in param.get("fiber_map", [])]
         param = Parameters.strip_params_dict(param)
         param["datetime"] = datetime_module.datetime.now()
         param["version"] = __version__
@@ -816,7 +808,9 @@ class Configuration:
         self.overwrite = overwrite
         self.final_path, self.fiber_configs = utils.load_config_sequence(final_config_path)
         self.final_path = utils.ensure_folder(
-            self.final_path, mkdir=False, prevent_overwrite=not self.overwrite
+            Path(env.get(env.OUTPUT_PATH, self.final_path)),
+            mkdir=False,
+            prevent_overwrite=not self.overwrite,
         )
         self.master_config = self.fiber_configs[0]
         self.name = self.final_path.name
@@ -868,23 +862,8 @@ class Configuration:
     def __iter__(self) -> Generator[tuple[VariationDescriptor, Parameters], None, None]:
         for i in range(self.num_fibers):
             for sim_config in self.iterate_single_fiber(i):
-
-                if i > 0:
-                    sim_config.config["prev_data_dir"] = str(
-                        self.fiber_paths[i - 1] / sim_config.descriptor[:i].formatted_descriptor()
-                    )
                 params = Parameters(**sim_config.config)
                 params.compute()
-                fiber_map = []
-                for j in range(i + 1):
-                    this_conf = self.all_configs[sim_config.descriptor.index[: j + 1]].config
-                    if j > 0:
-                        prev_conf = self.all_configs[sim_config.descriptor.index[:j]].config
-                        length = prev_conf["length"] + fiber_map[j - 1][0]
-                    else:
-                        length = 0.0
-                    fiber_map.append((length, this_conf["name"]))
-                params.fiber_map = fiber_map
                 yield sim_config.descriptor, params
 
     def iterate_single_fiber(
@@ -903,18 +882,21 @@ class Configuration:
         __SimConfig
             configuration obj
         """
-        sim_dict: dict[Path, self.__SimConfig] = {}
-        for descr in self.variationer.iterate(index):
-            cfg = descr.update_config(self.fiber_configs[index])
-            p = ensure_folder(
-                self.fiber_paths[index] / descr.formatted_descriptor(),
+        sim_dict: dict[Path, Configuration.__SimConfig] = {}
+        for descriptor in self.variationer.iterate(index):
+            cfg = descriptor.update_config(self.fiber_configs[index])
+            if index > 0:
+                cfg["prev_data_dir"] = str(
+                    self.fiber_paths[index - 1] / descriptor[:index].formatted_descriptor(True)
+                )
+            p = utils.ensure_folder(
+                self.fiber_paths[index] / descriptor.formatted_descriptor(True),
                 not self.overwrite,
                 False,
             )
             cfg["output_path"] = str(p)
-            sim_config = self.__SimConfig(descr, cfg, p)
-            sim_dict[p] = sim_config
-            self.all_configs[sim_config.descriptor.index] = sim_config
+            sim_config = self.__SimConfig(descriptor, cfg, p)
+            sim_dict[p] = self.all_configs[sim_config.descriptor.index] = sim_config
         while len(sim_dict) > 0:
             for data_dir, sim_config in sim_dict.items():
                 task, config_dict = self.__decide(sim_config)
@@ -1001,9 +983,12 @@ class Configuration:
             raise ValueError(f"Too many spectra in {data_dir}")
 
     def save_parameters(self):
-        for config, sim_dir in zip(self.fiber_configs, self.fiber_paths):
-            os.makedirs(sim_dir, exist_ok=True)
-            utils.save_toml(sim_dir / f"initial_config.toml", config)
+        os.makedirs(self.final_path, exist_ok=True)
+        cfgs = [
+            cfg | dict(variable=self.variationer.all_dicts[i])
+            for i, cfg in enumerate(self.fiber_configs)
+        ]
+        utils.save_toml(self.final_path / f"initial_config.toml", dict(name=self.name, Fiber=cfgs))
 
     @property
     def first(self) -> Parameters:
diff --git a/src/scgenerator/utils/utils.py b/src/scgenerator/_utils/utils.py
similarity index 69%
rename from src/scgenerator/utils/utils.py
rename to src/scgenerator/_utils/utils.py
index a18aacb..44eadf3 100644
--- a/src/scgenerator/utils/utils.py
+++ b/src/scgenerator/_utils/utils.py
@@ -1,12 +1,17 @@
 import inspect
+import os
 import re
+from collections import defaultdict
 from functools import cache
+from pathlib import Path
 from string import printable as str_printable
 from typing import Callable
 
 import numpy as np
 from pydantic import BaseModel
 
+from .._utils import load_toml, save_toml
+from ..const import PARAM_FN, Z_FN
 from ..physics.units import get_unit
 
 
@@ -144,3 +149,55 @@ def _mock_function(num_args: int, num_returns: int) -> Callable:
     out_func = scope[func_name]
     out_func.__module__ = "evaluator"
     return out_func
+
+
+def combine_simulations(path: Path, dest: Path = None):
+    """combines raw simulations into one folder per branch
+
+    Parameters
+    ----------
+    path : Path
+        source of the simulations (must contain u_xx directories)
+    dest : Path, optional
+        if given, moves the simulations to dest, by default None
+    """
+    paths: dict[str, list[Path]] = defaultdict(list)
+    if dest is None:
+        dest = path
+
+    for p in path.glob("u_*b_*"):
+        if p.is_dir():
+            paths[p.name.split()[1]].append(p)
+    for l in paths.values():
+        l.sort(key=lambda el: re.search(r"(?<=num )[0-9]+", el.name)[0])
+    for pulses in paths.values():
+        new_path = dest / update_path(pulses[0].name)
+        os.makedirs(new_path, exist_ok=True)
+        for num, pulse in enumerate(pulses):
+            params_ok = False
+            for file in pulse.glob("*"):
+                if file.name == PARAM_FN:
+                    if not params_ok:
+                        update_params(new_path, file)
+                        params_ok = True
+                    else:
+                        file.unlink()
+                elif file.name == Z_FN:
+                    file.rename(new_path / file.name)
+                else:
+                    file.rename(new_path / (file.stem + f"_{num}" + file.suffix))
+            pulse.rmdir()
+
+
+def update_params(new_path: Path, file: Path):
+    params = load_toml(file)
+    if (p := params.get("prev_data_dir")) is not None:
+        p = Path(p)
+        params["prev_data_dir"] = str(p.parent / update_path(p.name))
+    params["output_path"] = str(new_path)
+    save_toml(new_path / PARAM_FN, params)
+    file.unlink()
+
+
+def update_path(p: str) -> str:
+    return re.sub(r"( ?num [0-9]+)|(u_[0-9]+ )", "", p)
diff --git a/src/scgenerator/utils/variationer.py b/src/scgenerator/_utils/variationer.py
similarity index 87%
rename from src/scgenerator/utils/variationer.py
rename to src/scgenerator/_utils/variationer.py
index d53777d..fdd6368 100644
--- a/src/scgenerator/utils/variationer.py
+++ b/src/scgenerator/_utils/variationer.py
@@ -116,6 +116,7 @@ class VariationDescriptor(utils.HashableBaseModel):
     index: tuple[tuple[int, ...], ...]
     separator: str = "fiber"
     _format_registry: dict[str, Callable[..., str]] = {}
+    __ids: dict[int, int] = {}
 
     def __str__(self) -> str:
         return self.formatted_descriptor(add_identifier=False)
@@ -173,7 +174,19 @@ class VariationDescriptor(utils.HashableBaseModel):
             raw_descr=self.raw_descr[key], index=self.index[key], separator=self.separator
         )
 
-    def update_config(self, cfg: dict[str, Any]):
+    def update_config(self, cfg: dict[str, Any]) -> dict[str, Any]:
+        """updates a dictionary with the value of the descriptor
+
+        Parameters
+        ----------
+        cfg : dict[str, Any]
+            dict to be updated
+
+        Returns
+        -------
+        dict[str, Any]
+            same as cfg but with key from the descriptor added/updated.
+        """
         return cfg | {k: v for k, v in self.raw_descr[-1]}
 
     @property
@@ -188,17 +201,22 @@ class VariationDescriptor(utils.HashableBaseModel):
 
     @property
     def branch(self) -> "BranchDescriptor":
-        for i in reversed(range(len(self.raw_descr))):
-            for j in reversed(range(len(self.raw_descr[i]))):
-                if self.raw_descr[i][j][0] == "num":
-                    del self.raw_descr[i][j]
-        return VariationDescriptor(
-            raw_descr=self.raw_descr, index=self.index, separator=self.separator
-        )
+        descr = []
+        ind = []
+        for i, l in enumerate(self.raw_descr):
+            descr.append([])
+            ind.append([])
+            for j, (k, v) in enumerate(l):
+                if k != "num":
+                    descr[-1].append((k, v))
+                    ind[-1].append(self.index[i][j])
+        return BranchDescriptor(raw_descr=descr, index=ind, separator=self.separator)
 
     @property
     def identifier(self) -> str:
-        return "u_" + utils.to_62(hash(str(self.flat)))
+        unique_id = hash(str(self.flat))
+        self.__ids.setdefault(unique_id, len(self.__ids))
+        return "u_" + str(self.__ids[unique_id])
 
 
 class BranchDescriptor(VariationDescriptor):
@@ -208,7 +226,7 @@ class BranchDescriptor(VariationDescriptor):
     def identifier(self) -> str:
         branch_id = hash(str(self.flat))
         self.__ids.setdefault(branch_id, len(self.__ids))
-        return str(self.__ids[branch_id])
+        return "b_" + str(self.__ids[branch_id])
 
     @validator("raw_descr")
     def validate_raw_descr(cls, v):
diff --git a/src/scgenerator/cli/cli.py b/src/scgenerator/cli/cli.py
index 2532fdf..92b81ab 100644
--- a/src/scgenerator/cli/cli.py
+++ b/src/scgenerator/cli/cli.py
@@ -1,14 +1,13 @@
 import argparse
 import os
 import re
-import subprocess
-import sys
 from collections import ChainMap
 from pathlib import Path
 
 import numpy as np
 
-from .. import const, env, scripts, utils
+from .. import const, env, scripts
+from .. import _utils as utils
 from ..logger import get_logger
 from ..physics.fiber import dispersion_coefficients
 from ..physics.simulate import SequencialSimulations, run_simulation
diff --git a/src/scgenerator/const.py b/src/scgenerator/const.py
index c679236..b8843a2 100644
--- a/src/scgenerator/const.py
+++ b/src/scgenerator/const.py
@@ -20,7 +20,8 @@ def pbar_format(worker_id: int):
 
 
 SPEC1_FN = "spectrum_{}.npy"
-SPECN_FN = "spectra_{}.npy"
+SPECN_FN1 = "spectra_{}.npy"
+SPEC1_FN_N = "spectrum_{}_{}.npy"
 Z_FN = "z.npy"
 PARAM_FN = "params.toml"
 PARAM_SEPARATOR = " "
diff --git a/src/scgenerator/env.py b/src/scgenerator/env.py
index 46c0d6e..13f3545 100644
--- a/src/scgenerator/env.py
+++ b/src/scgenerator/env.py
@@ -48,7 +48,7 @@ def data_folder(task_id: int) -> Optional[str]:
     return tmp
 
 
-def get(key: str) -> Any:
+def get(key: str, default=None) -> Any:
     str_value = os.environ.get(key)
     if isinstance(str_value, str):
         try:
@@ -58,7 +58,7 @@ def get(key: str) -> Any:
             return t(str_value)
         except (ValueError, KeyError):
             pass
-    return None
+    return default
 
 
 def all_environ() -> Dict[str, str]:
diff --git a/src/scgenerator/math.py b/src/scgenerator/math.py
index 20db3dc..505c6b7 100644
--- a/src/scgenerator/math.py
+++ b/src/scgenerator/math.py
@@ -3,7 +3,7 @@ from typing import Union
 import numpy as np
 from scipy.interpolate import griddata, interp1d
 from scipy.special import jn_zeros
-from .utils.cache import np_cache
+from ._utils.cache import np_cache
 
 pi = np.pi
 c = 299792458.0
diff --git a/src/scgenerator/physics/__init__.py b/src/scgenerator/physics/__init__.py
index 82bc01e..24c3937 100644
--- a/src/scgenerator/physics/__init__.py
+++ b/src/scgenerator/physics/__init__.py
@@ -10,8 +10,8 @@ from scipy.optimize import minimize_scalar
 
 from .. import math
 from . import fiber, materials, units, pulse
-from .. import utils
-from ..utils import cache
+from .. import _utils
+from .._utils import cache
 
 T = TypeVar("T")
 
diff --git a/src/scgenerator/physics/fiber.py b/src/scgenerator/physics/fiber.py
index ccddbb1..4a27249 100644
--- a/src/scgenerator/physics/fiber.py
+++ b/src/scgenerator/physics/fiber.py
@@ -7,9 +7,9 @@ from scipy.interpolate import interp1d
 
 from ..logger import get_logger
 
-from .. import utils
+from .. import _utils
 from ..math import abs2, argclosest, power_fact, u_nm
-from ..utils.cache import np_cache
+from .._utils.cache import np_cache
 from . import materials as mat
 from . import units
 from .units import c, pi
diff --git a/src/scgenerator/physics/materials.py b/src/scgenerator/physics/materials.py
index 812e60e..b9572e6 100644
--- a/src/scgenerator/physics/materials.py
+++ b/src/scgenerator/physics/materials.py
@@ -5,7 +5,7 @@ from scipy.integrate import cumulative_trapezoid
 
 from ..logger import get_logger
 from . import units
-from .. import utils
+from .. import _utils
 from .units import NA, c, kB, me, e, hbar
 
 
diff --git a/src/scgenerator/physics/pulse.py b/src/scgenerator/physics/pulse.py
index 6a07c70..ce8ab29 100644
--- a/src/scgenerator/physics/pulse.py
+++ b/src/scgenerator/physics/pulse.py
@@ -23,8 +23,6 @@ from scipy.interpolate import UnivariateSpline
 from scipy.optimize import minimize_scalar
 from scipy.optimize.optimize import OptimizeResult
 
-from scgenerator import utils
-
 from ..defaults import default_plotting
 from ..logger import get_logger
 from ..math import *
diff --git a/src/scgenerator/physics/simulate.py b/src/scgenerator/physics/simulate.py
index 477d9c5..46b9897 100644
--- a/src/scgenerator/physics/simulate.py
+++ b/src/scgenerator/physics/simulate.py
@@ -9,9 +9,11 @@ from typing import Any, Generator, Type, Union
 import numpy as np
 from send2trash import send2trash
 
-from .. import env, utils
+from .. import env
+from .. import _utils as utils
+from .._utils.utils import combine_simulations
 from ..logger import get_logger
-from ..utils.parameter import Configuration, Parameters
+from .._utils.parameter import Configuration, Parameters
 from . import pulse
 from .fiber import create_non_linear_op, fast_dispersion_op
 
@@ -718,17 +720,9 @@ def run_simulation(
 
     sim = new_simulation(config, method)
     sim.run()
-    path_trees = utils.build_path_trees(config.fiber_paths[-1])
 
-    final_name = env.get(env.OUTPUT_PATH)
-    if final_name is None:
-        final_name = config.final_path
-
-    utils.merge(final_name, path_trees)
-    try:
-        send2trash(config.fiber_paths)
-    except (PermissionError, OSError):
-        get_logger(__name__).error("Could not send temporary directories to trash")
+    for path in config.fiber_paths:
+        combine_simulations(path)
 
 
 def new_simulation(
diff --git a/src/scgenerator/physics/units.py b/src/scgenerator/physics/units.py
index 80089fe..f648bb9 100644
--- a/src/scgenerator/physics/units.py
+++ b/src/scgenerator/physics/units.py
@@ -2,7 +2,6 @@
 # For example, nm(X) means "I give the number X in nm, figure out the ang. freq."
 # to be used especially when giving plotting ranges : (400, 1400, nm), (-4, 8, ps), ...
 
-from dataclasses import dataclass
 from typing import Callable, TypeVar, Union
 
 import numpy as np
diff --git a/src/scgenerator/plotting.py b/src/scgenerator/plotting.py
index 712bf12..6163520 100644
--- a/src/scgenerator/plotting.py
+++ b/src/scgenerator/plotting.py
@@ -14,8 +14,8 @@ from .const import PARAM_SEPARATOR
 from .defaults import default_plotting as defaults
 from .math import abs2, span
 from .physics import pulse, units
-from .utils.parameter import Parameters
-from .utils.utils import PlotRange, sort_axis
+from ._utils.parameter import Parameters
+from ._utils.utils import PlotRange, sort_axis
 
 RangeType = tuple[float, float, Union[str, Callable]]
 NO_LIM = object()
diff --git a/src/scgenerator/scripts/__init__.py b/src/scgenerator/scripts/__init__.py
index 029268f..176f236 100644
--- a/src/scgenerator/scripts/__init__.py
+++ b/src/scgenerator/scripts/__init__.py
@@ -12,12 +12,11 @@ from ..const import PARAM_FN, PARAM_SEPARATOR
 from ..physics import fiber, units
 from ..plotting import plot_setup
 from ..spectra import Pulse
-from ..utils import auto_crop, open_config, save_toml, translate_parameters
-from ..utils.parameter import (
+from .._utils import auto_crop, open_config, save_toml, translate_parameters
+from .._utils.parameter import (
     Configuration,
     Parameters,
 )
-from ..utils.variationer import VariationDescriptor
 
 
 def fingerprint(params: Parameters):
diff --git a/src/scgenerator/scripts/slurm_submit.py b/src/scgenerator/scripts/slurm_submit.py
index a977f35..3fc4b6b 100644
--- a/src/scgenerator/scripts/slurm_submit.py
+++ b/src/scgenerator/scripts/slurm_submit.py
@@ -9,8 +9,8 @@ from typing import Tuple
 
 import numpy as np
 
-from ..utils import Paths
-from ..utils.parameter import Configuration
+from .._utils import Paths
+from .._utils.parameter import Configuration
 
 
 def primes(n):
diff --git a/src/scgenerator/spectra.py b/src/scgenerator/spectra.py
index fdd6b78..82a83b8 100644
--- a/src/scgenerator/spectra.py
+++ b/src/scgenerator/spectra.py
@@ -1,13 +1,19 @@
+from __future__ import annotations
+
 import os
 from collections.abc import Sequence
 from pathlib import Path
-from typing import Callable, Dict, Iterable, Optional, Union
+from typing import Any, Callable, Dict, Iterable, Optional, Union
 
 import matplotlib.pyplot as plt
 import numpy as np
+from pydantic import BaseModel, DirectoryPath, root_validator
 
 from . import math
-from .const import SPECN_FN
+from ._utils import load_spectrum
+from ._utils.parameter import Parameters
+from ._utils.utils import PlotRange
+from .const import SPECN_FN1, PARAM_FN, SPEC1_FN_N
 from .logger import get_logger
 from .physics import pulse, units
 from .plotting import (
@@ -16,9 +22,87 @@ from .plotting import (
     single_position_plot,
     transform_2D_propagation,
 )
-from .utils.parameter import Parameters
-from .utils.utils import PlotRange
-from .utils import load_spectrum
+
+
+class SimulationSeries:
+    path: Path
+    params: Parameters
+    total_length: float
+    total_num_steps: int
+    previous: SimulationSeries = None
+
+    class Config:
+        arbitrary_types_allowed = True
+
+    def __init__(self, path: os.PathLike):
+        self.path = Path(path)
+        self.params = Parameters.load(self.path / PARAM_FN)
+        if self.params.prev_data_dir is not None:
+            self.previous = SimulationSeries(self.params.prev_data_dir)
+        self.total_length = self.accumulate_params("length")
+        self.total_num_steps = self.accumulate_params("z_num")
+
+    def fiber_map(self):
+        lengths = self.all_params("length")
+        return [
+            (this[0], following[1]) for this, following in zip(lengths, [(None, 0.0)] + lengths)
+        ]
+
+    def all_params(self, key: str) -> list[tuple[str, Any]]:
+        """returns the value of a parameter for each fiber
+
+        Parameters
+        ----------
+        key : str
+            name of the parameter
+
+        Returns
+        -------
+        list[tuple[str, Any]]
+            list of (fiber_name, param_value) tuples
+        """
+        return list(reversed(self._all_params(key, [])))
+
+    def accumulate_params(self, key: str) -> Any:
+        """returns the sum of all the values a parameter takes. Useful to
+        get the total length of the fiber, the total number of steps, etc.
+
+        Parameters
+        ----------
+        key : str
+            name of the parameter
+
+        Returns
+        -------
+        Any
+            final sum
+        """
+        return sum(el[1] for el in self.all_params(key))
+
+    def _load_1(self, z_ind: int, sim_ind=0) -> np.ndarray:
+        return load_spectrum(self.path / SPEC1_FN_N.format(z_ind, sim_ind))
+
+    def _all_params(self, key: str, l: list) -> list:
+        l.append((self.params.name, getattr(self.params, key)))
+        if self.previous is not None:
+            return self.previous._all_params(key, l)
+        return l
+
+    def __repr__(self) -> str:
+        return f"{self.__class__.__name__}(path={self.path}, previous={self.previous!r})"
+
+    def __eq__(self, other: SimulationSeries) -> bool:
+        return (
+            self.path == other.path
+            and self.params == other.params
+            and self.previous == other.previous
+        )
+
+    def __contains__(self, other: SimulationSeries) -> bool:
+        if other is self or other == self:
+            return True
+        if self.previous is not None:
+            return other in self.previous
 
 
 class Spectrum(np.ndarray):
@@ -129,6 +213,23 @@ class Spectrum(np.ndarray):
 
 
 class Pulse(Sequence):
+    path: Path
+    default_ind: Optional[int]
+    params: Parameters
+    z: np.ndarray
+    namx: int
+    t: np.ndarray
+    w: np.ndarray
+    w_order: np.ndarray
+
+    def __new__(cls, path: os.PathLike, *args, **kwargs) -> "Pulse":
+        try:
+            if load_spectrum(Path(path) / SPECN_FN1.format(0)).ndim == 2:
+                return super().__new__(LegacyPulse)
+        except FileNotFoundError:
+            pass
+        return super().__new__(cls)
+
     def __init__(self, path: os.PathLike, default_ind: Union[int, Iterable[int]] = None):
         """load a data folder as a pulse
 
@@ -144,36 +245,6 @@ class Pulse(Sequence):
         FileNotFoundError
             path does not contain proper data
         """
-        self.logger = get_logger(__name__)
-        self.path = Path(path)
-        self.default_ind = default_ind
-
-        if not self.path.is_dir():
-            raise FileNotFoundError(f"Folder {self.path} does not exist")
-
-        self.params = Parameters.load(self.path / "params.toml")
-        self.params.compute(["name", "t", "l", "w_c", "w0", "z_targets"])
-        if self.params.fiber_map is None:
-            self.params.fiber_map = [(0.0, self.params.name)]
-
-        try:
-            self.z = np.load(os.path.join(path, "z.npy"))
-        except FileNotFoundError:
-            if self.params is not None:
-                self.z = self.params.z_targets
-            else:
-                raise
-        self.nmax = len(list(self.path.glob("spectra_*.npy")))
-        if self.nmax <= 0:
-            raise FileNotFoundError(f"No appropriate file in specified folder {self.path}")
-
-        self.t = self.params.t
-        w = math.wspace(self.t) + units.m(self.params.wavelength)
-        self.w_order = np.argsort(w)
-        self.w = w
-        self.wl = units.m.inv(self.w)
-        self.params.w = self.w
-        self.params.z_targets = self.z
 
     def __iter__(self):
         """
@@ -190,73 +261,6 @@ class Pulse(Sequence):
     def __getitem__(self, key) -> Spectrum:
         return self.all_spectra(key)
 
-    def intensity(self, unit):
-        if unit.type in ["WL", "FREQ", "AFREQ"]:
-            x_axis = unit.inv(self.w)
-        else:
-            x_axis = unit.inv(self.t)
-
-        order = np.argsort(x_axis)
-        func = dict(
-            WL=self._to_wl_int,
-            FREQ=self._to_freq_int,
-            AFREQ=self._to_afreq_int,
-            TIME=self._to_time_int,
-        )[unit.type]
-
-        for spec in self:
-            yield x_axis[order], func(spec)[:, order]
-
-    def _to_wl_int(self, spectrum):
-        return units.to_WL(math.abs2(spectrum), spectrum.wl)
-
-    def _to_freq_int(self, spectrum):
-        return math.abs2(spectrum)
-
-    def _to_afreq_int(self, spectrum):
-        return math.abs2(spectrum)
-
-    def _to_time_int(self, spectrum):
-        return math.abs2(np.fft.ifft(spectrum))
-
-    def amplitude(self, unit):
-        if unit.type in ["WL", "FREQ", "AFREQ"]:
-            x_axis = unit.inv(self.w)
-        else:
-            x_axis = unit.inv(self.t)
-
-        order = np.argsort(x_axis)
-        func = dict(
-            WL=self._to_wl_amp,
-            FREQ=self._to_freq_amp,
-            AFREQ=self._to_afreq_amp,
-            TIME=self._to_time_amp,
-        )[unit.type]
-
-        for spec in self:
-            yield x_axis[order], func(spec)[:, order]
-
-    def _to_wl_amp(self, spectrum):
-        return (
-            np.sqrt(
-                units.to_WL(
-                    math.abs2(spectrum),
-                    spectrum.wl,
-                )
-            )
-            * spectrum
-            / np.abs(spectrum)
-        )
-
-    def _to_freq_amp(self, spectrum):
-        return spectrum
-
-    def _to_afreq_amp(self, spectrum):
-        return spectrum
-
-    def _to_time_amp(self, spectrum):
-        return np.fft.ifft(spectrum)
-
     def all_spectra(self, ind=None) -> Spectrum:
         """
         loads the data already simulated.
@@ -305,12 +309,7 @@ class Pulse(Sequence):
         return np.fft.ifft(self.all_spectra(ind=ind), axis=-1)
 
     def _load1(self, i: int):
-        if i < 0:
-            i = self.nmax + i
-        spec = load_spectrum(self.path / SPECN_FN.format(i))
-        spec = np.atleast_2d(spec)
-        spec = Spectrum(spec, self.params)
-        return spec
+        pass
 
     def plot_2D(
         self,
@@ -412,3 +411,46 @@ class Pulse(Sequence):
             index
         """
         return math.argclosest(self.z, z)
+
+
+class LegacyPulse(Pulse):
+    def __init__(self, path: os.PathLike, default_ind: Union[int, Iterable[int]] = None):
+        print("old init called", path, default_ind)
+        self.logger = get_logger(__name__)
+        self.path = Path(path)
+        self.default_ind = default_ind
+
+        if not self.path.is_dir():
+            raise FileNotFoundError(f"Folder {self.path} does not exist")
+
+        self.params = Parameters.load(self.path / "params.toml")
+        self.params.compute(["name", "t", "l", "w_c", "w0", "z_targets"])
+        if self.params.fiber_map is None:
+            self.params.fiber_map = [(0.0, self.params.name)]
+
+        try:
+            self.z = np.load(os.path.join(path, "z.npy"))
+        except FileNotFoundError:
+            if self.params is not None:
+                self.z = self.params.z_targets
+            else:
+                raise
+        self.nmax = len(list(self.path.glob("spectra_*.npy")))
+        if self.nmax <= 0:
+            raise FileNotFoundError(f"No appropriate file in specified folder {self.path}")
+
+        self.t = self.params.t
+        w = math.wspace(self.t) + units.m(self.params.wavelength)
+        self.w_order = np.argsort(w)
+        self.w = w
+        self.wl = units.m.inv(self.w)
+        self.params.w = self.w
+        self.params.z_targets = self.z
+
+    def _load1(self, i: int):
+        if i < 0:
+            i = self.nmax + i
+        spec = load_spectrum(self.path / SPECN_FN1.format(i))
+        spec = np.atleast_2d(spec)
+        spec = Spectrum(spec, self.params)
+        return spec
diff --git a/testing/long_tests/test_recovery_param_seq.py b/testing/long_tests/test_recovery_param_seq.py
deleted file mode 100644
index 5d73367..0000000
--- a/testing/long_tests/test_recovery_param_seq.py
+++ /dev/null
@@ -1,35 +0,0 @@
-import shutil
-import unittest
-
-import toml
-from scgenerator import logger
-from send2trash import send2trash
-
-TMP = "testing/.tmp"
-
-
-class TestRecoveryParamSequence(unittest.TestCase):
-    def setUp(self):
-        shutil.copytree("/Users/benoitsierro/sc_tests/scgenerator_full anomalous55", TMP)
-        self.conf = toml.load(TMP + "/initial_config.toml")
-        io.set_data_folder(55, TMP)
-
-    def test_remaining_simulations_count(self):
-        param_seq = initialize.RecoveryParamSequence(self.conf, 55)
-        self.assertEqual(5, len(param_seq))
-
-    def test_only_one_to_complete(self):
-        param_seq = initialize.RecoveryParamSequence(self.conf, 55)
-        i = 0
-        for expected, (vary_list, params) in zip([True, False, False, False, False], param_seq):
-            i += 1
-            self.assertEqual(expected, "recovery_last_stored" in params)
-
-        self.assertEqual(5, i)
-
-    def tearDown(self):
-        send2trash(TMP)
-
-
-if __name__ == "__main__":
-    unittest.main()
diff --git a/testing/test_initialize.py b/testing/test_initialize.py
deleted file mode 100644
index edd3d90..0000000
--- a/testing/test_initialize.py
+++ /dev/null
@@ -1,216 +0,0 @@
-import unittest
-from copy import deepcopy
-
-import numpy as np
-import toml
-from scgenerator import defaults, utils, math
-from scgenerator.errors import *
-from scgenerator.physics import pulse, units
-from scgenerator.utils.parameter import Config, Parameters
-
-
-def load_conf(name):
-    with open("testing/configs/" + name + ".toml") as file:
-        conf = toml.load(file)
-    return conf
-
-
-def conf_maker(folder):
-    def conf(name):
-        return load_conf(folder + "/" + name)
-
-    return conf
-
-
-class TestParamSequence(unittest.TestCase):
-    def iterconf(self, files):
-        conf = conf_maker("param_sequence")
-        for path in files:
-            yield init.ParamSequence(conf(path))
-
-    def test_no_repeat_in_sub_folder_names(self):
-        for param_seq in self.iterconf(["almost_equal", "equal", "no_variations"]):
-            l = []
-            s = []
-            for vary_list, _ in utils.required_simulations(param_seq.config):
-                self.assertNotIn(vary_list, l)
-                self.assertNotIn(utils.format_variable_list(vary_list), s)
-                l.append(vary_list)
-                s.append(utils.format_variable_list(vary_list))
-
-    def test_no_variations_yields_only_num_and_id(self):
-        for param_seq in self.iterconf(["no_variations"]):
-            for vary_list, _ in utils.required_simulations(param_seq.config):
-                self.assertEqual(vary_list[1][0], "num")
-                self.assertEqual(vary_list[0][0], "id")
-                self.assertEqual(2, len(vary_list))
-
-
-class TestInitializeMethods(unittest.TestCase):
-    def test_validate_types(self):
-        conf = lambda s: load_conf("validate_types/" + s)
-
-        with self.assertRaisesRegex(ValueError, r"'behaviors\[3\]' must be a str in"):
-            init.Config(**conf("bad2"))
-
-        with self.assertRaisesRegex(TypeError, "value must be of type <class 'float'>"):
-            init.Config(**conf("bad3"))
-
-        with self.assertRaisesRegex(TypeError, "'parallel' is not a valid variable parameter"):
-            init.Config(**conf("bad4"))
-
-        with self.assertRaisesRegex(
-            TypeError, "'variable intensity_noise' value must be of type <class 'list'>"
-        ):
-            init.Config(**conf("bad5"))
-
-        with self.assertRaisesRegex(ValueError, "'repeat' must be positive"):
-            init.Config(**conf("bad6"))
-
-        with self.assertRaisesRegex(
-            ValueError, "variable parameter 'intensity_noise' must not be empty"
-        ):
-            init.Config(**conf("bad7"))
-
-        self.assertIsNone(init.Config(**conf("good")).hr_w)
-
-    def test_ensure_consistency(self):
-        conf = lambda s: load_conf("ensure_consistency/" + s)
-        with self.assertRaisesRegex(
-            MissingParameterError,
-            r"1 of '\['t0', 'width'\]' is required and no defaults have been set",
-        ):
-            init.Config(**conf("bad1"))
-
-        with self.assertRaisesRegex(
-            MissingParameterError,
-            r"1 of '\['peak_power', 'mean_power', 'energy', 'width', 't0'\]' is required when 'soliton_num' is specified and no defaults have been set",
-        ):
-            init.Config(**conf("bad2"))
-
-        with self.assertRaisesRegex(
-            MissingParameterError,
-            r"2 of '\['dt', 't_num', 'time_window'\]' are required and no defaults have been set",
-        ):
-            init.Config(**conf("bad3"))
-
-        with self.assertRaisesRegex(
-            DuplicateParameterError,
-            r"got multiple values for parameter 'width'",
-        ):
-            init.Config(**conf("bad4"))
-
-        with self.assertRaisesRegex(
-            MissingParameterError,
-            r"'capillary_thickness' is a required parameter for fiber model 'hasan' and no defaults have been set",
-        ):
-            init.Config(**conf("bad5"))
-
-        with self.assertRaisesRegex(
-            MissingParameterError,
-            r"1 of '\['capillary_spacing', 'capillary_outer_d'\]' is required for fiber model 'hasan' and no defaults have been set",
-        ):
-            init.Config(**conf("bad6"))
-
-        self.assertLessEqual(
-            {"model": "pcf"}.items(), init.Config(**conf("good1")).__dict__.items()
-        )
-
-        self.assertIsNone(init.Config(**conf("good4")).gamma)
-
-        self.assertLessEqual(
-            {"raman_type": "agrawal"}.items(),
-            init.Config(**conf("good2")).__dict__.items(),
-        )
-
-        self.assertLessEqual(
-            {"name": "no name"}.items(), init.Config(**conf("good3")).__dict__.items()
-        )
-
-        self.assertLessEqual(
-            {"capillary_nested": 0, "capillary_resonance_strengths": []}.items(),
-            init.Config(**conf("good4")).__dict__.items(),
-        )
-
-        self.assertLessEqual(
-            dict(he_mode=(1, 1)).items(),
-            init.Config(**conf("good5")).__dict__.items(),
-        )
-
-        self.assertLessEqual(
-            dict(temperature=300, pressure=1e5, gas_name="vacuum", plasma_density=0).items(),
-            init.Config(**conf("good5")).__dict__.items(),
-        )
-
-    def setup_conf_custom_field(self, path) -> Parameters:
-
-        conf = load_conf(path)
-        conf = Parameters(**conf)
-        init.build_sim_grid_in_place(conf)
-        return conf
-
-    def test_setup_custom_field(self):
-        d = np.load("testing/configs/custom_field/init_field.npz")
-        t = d["time"]
-        field = d["field"]
-        conf = self.setup_conf_custom_field("custom_field/no_change")
-        result, conf.width, conf.peak_power, conf.energy, conf.field_0 = pulse.setup_custom_field(
-            conf
-        )
-        self.assertAlmostEqual(conf.field_0.real.max(), field.real.max(), 4)
-        self.assertTrue(result)
-
-        conf = self.setup_conf_custom_field("custom_field/peak_power")
-        result, conf.width, conf.peak_power, conf.energy, conf.field_0 = pulse.setup_custom_field(
-            conf
-        )
-        conf.wavelength = pulse.correct_wavelength(conf.wavelength, conf.w_c, conf.field_0)
-        self.assertAlmostEqual(math.abs2(conf.field_0).max(), 20000, 4)
-        self.assertTrue(result)
-        self.assertNotAlmostEqual(conf.wavelength, 1593e-9)
-
-        conf = self.setup_conf_custom_field("custom_field/mean_power")
-        result, conf.width, conf.peak_power, conf.energy, conf.field_0 = pulse.setup_custom_field(
-            conf
-        )
-        self.assertAlmostEqual(np.trapz(math.abs2(conf.field_0), conf.t), 0.22 / 40e6, 4)
-        self.assertTrue(result)
-
-        conf = self.setup_conf_custom_field("custom_field/recover1")
-        result, conf.width, conf.peak_power, conf.energy, conf.field_0 = pulse.setup_custom_field(
-            conf
-        )
-        self.assertAlmostEqual(math.abs2(conf.field_0 - field).sum(), 0)
-        self.assertTrue(result)
-
-        conf = self.setup_conf_custom_field("custom_field/recover2")
-        result, conf.width, conf.peak_power, conf.energy, conf.field_0 = pulse.setup_custom_field(
-            conf
-        )
-        self.assertAlmostEqual((math.abs2(conf.field_0) / 0.9 - math.abs2(field)).sum(), 0)
-        self.assertTrue(result)
-
-        conf = self.setup_conf_custom_field("custom_field/wavelength_shift1")
-        result = Parameters(**conf)
-        self.assertAlmostEqual(units.m.inv(result.w)[np.argmax(math.abs2(result.spec_0))], 1050e-9)
-
-        conf = self.setup_conf_custom_field("custom_field/wavelength_shift1")
-        conf.wavelength = 1593e-9
-        result = Parameters(**conf)
-
-        conf = load_conf("custom_field/wavelength_shift2")
-        conf = init.Config(**conf)
-        for target, (variable, config) in zip(
-            [1050e-9, 1321e-9, 1593e-9], init.ParamSequence(conf)
-        ):
-            init.build_sim_grid_in_place(conf)
-            self.assertAlmostEqual(
-                units.m.inv(config.w)[np.argmax(math.abs2(config.spec_0))], target
-            )
-            print(config.wavelength, target)
-
-
-if __name__ == "__main__":
-    conf = conf_maker("validate_types")
-
-    unittest.main()
diff --git a/testing/test_pulse.py b/testing/test_pulse.py
deleted file mode 100644
index 6a632d4..0000000
--- a/testing/test_pulse.py
+++ /dev/null
@@ -1,41 +0,0 @@
-import unittest
-from scgenerator.physics.pulse import conform_pulse_params
-
-
-class TestPulseMethods(unittest.TestCase):
-    def test_conform_pulse_params(self):
-        self.assertNotIn(None, conform_pulse_params("gaussian", t0=5, energy=6))
-        self.assertNotIn(None, conform_pulse_params("gaussian", width=5, energy=6))
-        self.assertNotIn(None, conform_pulse_params("gaussian", t0=5, peak_power=6))
-        self.assertNotIn(None, conform_pulse_params("gaussian", width=5, peak_power=6))
-
-        self.assertEqual(4, len(conform_pulse_params("gaussian", t0=5, energy=6)))
-        self.assertEqual(4, len(conform_pulse_params("gaussian", width=5, energy=6)))
-        self.assertEqual(4, len(conform_pulse_params("gaussian", t0=5, peak_power=6)))
-        self.assertEqual(4, len(conform_pulse_params("gaussian", width=5, peak_power=6)))
-
-        with self.assertRaisesRegex(
-            TypeError, "when soliton number is desired, both gamma and beta2 must be specified"
-        ):
-            conform_pulse_params("gaussian", t0=5, energy=6, gamma=0.01)
-        with self.assertRaisesRegex(
-            TypeError, "when soliton number is desired, both gamma and beta2 must be specified"
-        ):
-            conform_pulse_params("gaussian", t0=5, energy=6, beta2=0.01)
-
-        self.assertEqual(
-            5, len(conform_pulse_params("gaussian", t0=5, energy=6, gamma=0.01, beta2=2e-6))
-        )
-        self.assertEqual(
-            5, len(conform_pulse_params("gaussian", width=5, energy=6, gamma=0.01, beta2=2e-6))
-        )
-        self.assertEqual(
-            5, len(conform_pulse_params("gaussian", t0=5, peak_power=6, gamma=0.01, beta2=2e-6))
-        )
-        self.assertEqual(
-            5, len(conform_pulse_params("gaussian", width=5, peak_power=6, gamma=0.01, beta2=2e-6))
-        )
-
-
-if __name__ == "__main__":
-    unittest.main()
diff --git a/testing/test_utils.py b/testing/test_utils.py
deleted file mode 100644
index ef277eb..0000000
--- a/testing/test_utils.py
+++ /dev/null
@@ -1,67 +0,0 @@
-import unittest
-
-import numpy as np
-import toml
-from scgenerator import utils
-
-
-def load_conf(name):
-    with open("testing/configs/" + name + ".toml") as file:
-        conf = toml.load(file)
-    return conf
-
-
-def conf_maker(folder, val=True):
-    def conf(name):
-        if val:
-            return initialize.Config(**load_conf(folder + "/" + name))
-        else:
-            return initialize.Config(**load_conf(folder + "/" + name))
-
-    return conf
-
-
-class TestUtilsMethods(unittest.TestCase):
-    def test_count_variations(self):
-        conf = conf_maker("count_variations")
-
-        for sim, vary in [(1, 0), (1, 1), (2, 1), (2, 0), (120, 3)]:
-            self.assertEqual((sim, vary), utils.count_variations(conf(f"{sim}sim_{vary}vary")))
-
-    def test_format_value(self):
-        values = [
-            122e-6,
-            True,
-            ["raman", "ss"],
-            np.arange(5),
-            1.123,
-            1.1230001,
-            0.002e122,
-            12.3456e-9,
-        ]
-        s = [
-            "0.000122",
-            "True",
-            "raman-ss",
-            "0-1-2-3-4",
-            "1.123",
-            "1.1230001",
-            "2e+119",
-            "1.23456e-08",
-        ]
-
-        for value, target in zip(values, s):
-            self.assertEqual(target, utils.format_value(value))
-
-    def test_override_config(self):
-        conf = conf_maker("override", False)
-        old = conf("initial_config")
-        new = conf("fiber2")
-
-        over = utils.override_config(vars(new), old)
-        self.assertNotIn("input_transmission", over.variable)
-        self.assertIsNone(over.input_transmission)
-
-
-if __name__ == "__main__":
-    unittest.main()
diff --git a/testing/test_variationer.py b/testing/test_variationer.py
new file mode 100644
index 0000000..67033e2
--- /dev/null
+++ b/testing/test_variationer.py
@@ -0,0 +1,54 @@
+from pydantic import main
+import scgenerator as sc
+
+
+def test_descriptor():
+    # Same branch
+    var1 = sc.VariationDescriptor(
+        raw_descr=[[("num", 1), ("a", False)], [("b", 0)]], index=[[1, 0], [0]]
+    )
+    var2 = sc.VariationDescriptor(
+        raw_descr=[[("num", 2), ("a", False)], [("b", 0)]], index=[[1, 0], [0]]
+    )
+    assert var1.branch.identifier == "b_0"
+    assert var1.identifier != var1.branch.identifier
+    assert var1.identifier != var2.identifier
+    assert var1.branch.identifier == var2.branch.identifier
+
+    # different branch
+    var3 = sc.VariationDescriptor(
+        raw_descr=[[("num", 2), ("a", True)], [("b", 0)]], index=[[1, 0], [0]]
+    )
+    assert var1.branch.identifier != var3.branch.identifier
+    assert var1.formatted_descriptor() != var2.formatted_descriptor()
+    assert var1.formatted_descriptor() != var3.formatted_descriptor()
+
+
+def test_variationer():
+    var = sc.Variationer(
+        [
+            dict(a=[1, 2], num=[0, 1, 2]),
+            [dict(b=["000", "111"], c=["a", "-1"])],
+            dict(),
+            dict(),
+            [dict(aaa=[True, False], bb=[1, 3])],
+        ]
+    )
+    assert var.var_num(0) == 6
+    assert var.var_num(1) == 12
+    assert var.var_num() == 24
+
+    cfg = dict(bb=None)
+    branches = set()
+    for descr in var.iterate():
+        assert descr.update_config(cfg).items() >= set(descr.raw_descr[-1])
+        branches.add(descr.branch.identifier)
+    assert len(branches) == 8
+
+
+def main():
+    test_descriptor()
+
+
+if __name__ == "__main__":
+    main()