class_docstr: Sorting key for all galleries subsections
  
  This requires all folders to be listed otherwise an exception is raised
  
  Parameters
  ----------
  ordered_list : list, tuple, types.GeneratorType
      Hold the paths of each galleries' subsections
  
  Raises
  ------
  ValueError
      Wrong input type or Subgallery path missing
code: def __init__(self, ordered_list):
      if not isinstance(
          ordered_list, (list, tuple, types.GeneratorType)
      ):
          raise ValueError(
              "ExplicitOrder sorting key takes a list, "
              "tuple or Generator, which hold"
              "the paths of each gallery subfolder"
          )
  
      self.ordered_list = list(
          os.path.normpath(path) for path in ordered_list
      )
  
imports: from __future__ import division, absolute_import, print_function
  import os
  import types
label_desc: Use image node_id 1 to create a new ExplicitOrder object from inherited base classes: object with example: obj = ExplicitOrder(ordered_list)