code: def _simplify_cells(d):
      """Convert mat objects in dict to nested dicts."""
      for key in d:
          if isinstance(d[key], mat_struct):
              d[key] = _matstruct_to_dict(d[key])
          elif _has_struct(d[key]):
              d[key] = _inspect_cell_array(d[key])
      return d
  
imports: import os
  import time
  import sys
  import zlib
  from io import BytesIO
  import warnings
  import numpy
  import scipy.sparse
  from ._byteordercodes import native_code, swapped_code
  from ._miobase import MatFileReader, docfiller, matdims, read_dtype, arr_to_chars, arr_dtype_number, MatWriteError, MatReadError, MatReadWarning
  from ._mio5_utils import VarReader5
  from ._mio5_params import MatlabObject, MatlabFunction, MDTYPES, NP_TO_MTYPES, NP_TO_MXTYPES, miCOMPRESSED, miMATRIX, miINT8, miUTF8, miUINT32, mxCELL_CLASS, mxSTRUCT_CLASS, mxOBJECT_CLASS, mxCHAR_CLASS, mxSPARSE_CLASS, mxDOUBLE_CLASS, mclass_info, mat_struct
  from ._streams import ZlibInputStream
label_desc: Use image node_id 4 for calling a global function with example usage: _simplify_cells(d) and returns: d