code: def test_multiple_signals(self):
      class SimpleSignal(object):
          events = []
  
          def __init__(self, name):
              self.name = name
  
          def update_end(self, network):
              self.events.append(self.name)
  
      train_network(
          batch_size=10, signals=[SimpleSignal("a"), SimpleSignal("b")]
      )
  
      self.assertEqual(SimpleSignal.events, ["a", "b"] * 6)
  
imports: from __future__ import unicode_literals
  from collections import namedtuple
  import numpy
  import progressbar
  from sklearn.datasets import make_classification
  from neupy import algorithms, layers
  from neupy.exceptions import StopTraining
  from neupy.algorithms.signals import format_time
  from base import BaseTestCase
  from helpers import catch_stdout
label_desc: Use image node_id 4 for calling the SignalsTestCase obj's underlying member method code with example usage: obj.test_multiple_signals() without return types