code: def calc_idx_diff(idx, idx_nn):
      return idx_nn - idx
  
imports: from __future__ import absolute_import
  from __future__ import division
  from __future__ import print_function
  from __future__ import unicode_literals
  import math
  import time
  import warnings
  import numpy
label_desc: Use image node_id 11 for calling a global function with example usage: calc_idx_diff(idx, idx_nn) and returns: unknown