code: def epoch_start(self, network):
      self.index = 0
      self.last_train_error = None
      self.bar = progressbar.NullBar()
  
      if network.verbose and self.n_batches >= 2:
          self.bar = iters.make_progressbar(
              self.n_batches, show_output=True
          )
          self.bar.update(0)
  
imports: from __future__ import unicode_literals
  import time
  import progressbar
  from neupy.utils import iters
label_desc: Use image node_id 2 for calling the ProgressbarSignal obj's underlying member method code with example usage: obj.epoch_start(network) without return types