code: def error_function(expected, predicted):
      """
      Parameters
      ----------
      expected : array-like, tensorflow variable
      predicted : array-like, tensorflow variable
  
      Returns
      -------
      array-like, tensorflow variable
      """
      raise NotImplementedError
  
file_path: neupy/neupy/algorithms/gd/objectives.py
imports: from __future__ import division
  import tensorflow
  from neupy.core.docs import shared_docs
  from neupy.utils import asfloat, function_name_scope
label_desc: Use image node_id 1 for calling a global function with example usage: error_function(expected, predicted) without return types