code: def err(y, t):
      feature_axis = 1
      return 0.5 * np.square(y - t).mean(axis=feature_axis).mean()
  
file_path: neon/examples/timeseries/utils.py
imports: from __future__ import division
  import numpy
  import math
  from neon import NervanaObject
label_desc: Use image node_id 2 for calling a global function with example usage: err(y, t) and returns: unknown