code: def run_summaries(
          sess, merged_summaries, summary_writer, epoch, feed, tens):
      
      try:
          result = sess.run([merged_summaries, tens], feed_dict=feed)
          summary_str = result[0]
          out = result[1]
          summary_writer.add_summary(summary_str, epoch)
      except tf.errors.InvalidArgumentError:
          out = sess.run(tens, feed_dict=feed)
  
      return out
docs: Run the summaries and error computation on the validation set.
  
      Parameters
      ----------
  
      sess : tf.Session
          Tensorflow session object.
  
      merged_summaries : tf obj
          Tensorflow merged summaries obj.
  
      summary_writer : tf.summary.FileWriter
          Tensorflow summary writer obj.
  
      epoch : int
          Current training epoch.
  
      feed : dict
          Validation feed dict.
  
      tens : tf.Tensor
          Tensor to display and evaluate during training.
          Can be self.accuracy for SupervisedModel or self.cost for
          UnsupervisedModel.
  
      Returns
      -------
  
      err : float, mean error over the validation set.