code: def _reconstruct_flattened_structure(structure, flattened):
      
      if isinstance(structure, list):
          return list(_reconstruct_flattened_structure(x, flattened) for x in structure)
      elif isinstance(structure, tuple):
          return tuple(_reconstruct_flattened_structure(x, flattened) for x in structure)
      elif isinstance(structure, dict):
          return {k: _reconstruct_flattened_structure(v, flattened) for k, v in structure.items()}
      elif isinstance(structure, int):
          return flattened[structure]
      else:
          raise NotImplementedError
docs: Reconstruct the flattened list back to (possibly) nested structure.
  
      Parameters
      ----------
      structure : An integer or a nested container with integers.
          The extracted structure of the container of `data`.
      flattened : list or None
          The container thats holds flattened result.
      Returns
      -------
      data : A single NDArray/Symbol or nested container with NDArrays/Symbol.
          The nested container that was flattened.