code: def mse(expected, predicted):
      """
      Mean squared error.
  
      .. math::
          mse(t, o) = mean((t - o) ^ 2)
  
      where :math:`t=expected` and :math:`o=predicted`
  
      Parameters
      ----------
      {error_function.expected}
      {error_function.predicted}
  
      Returns
      -------
      {error_function.Returns}
      """
      return tf.reduce_mean(tf.square(predicted - expected))
  
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 2 for calling a global function with example usage: mse(expected, predicted) and returns: tf