code: def test_on_start(self, llp_mock):
      llp = LiveLossPlot(True, 1, True, False)
      llp.on_start({})
      self.assertTrue(llp_mock.call_count == 2)
  
file_path: torchbearer/tests/callbacks/test_live_loss_plot.py
imports: from unittest import TestCase
  from mock import patch, MagicMock
  import torchbearer
  from torchbearer.callbacks import LiveLossPlot
label_desc: Use image node_id 1 for calling the TestLiveLossPlot obj's underlying member method code with example usage: obj.test_on_start(llp_mock) without return types