class_docstr: Map indexes from one layer to the other.
  
  Parameters
  ----------
  input_size : tuple
      the input size
  output_size : tuple
      the mapped input layer's output size
code: def __init__(self, input_size, output_size):
      self.__input_size = input_size
      self.__output_size = output_size
  
imports: import itertools
  import numpy
label_desc: Use image node_id 1 to create a new IndexMapper object  with example: obj = IndexMapper(input_size, output_size)