code: def print_last_error(self, network):
      messages = []
      base_message = "#{} : [{}] ".format(
          network.last_epoch, format_time(self.last_epoch_time)
      )
  
      if self.last_train_error is not None:
          messages.append("train: {:.6f}".format(self.last_train_error))
  
      if self.last_valid_error is not None:
          messages.append("valid: {:.6f}".format(self.last_valid_error))
  
      network.logs.write(base_message + ", ".join(messages))
  
imports: from __future__ import unicode_literals
  import time
  import progressbar
  from neupy.utils import iters
label_desc: Use image node_id 1 for calling the PrintLastErrorSignal obj's underlying member method code with example usage: obj.print_last_error(network) without return types