code: def on_backward(self, state):
      super(TimerMetric, self).on_backward(state)
      self.update_time(ON_BACKWARD, self.batch_timer, state)
  
imports: from __future__ import print_function
  import sys
  import time
  from torchbearer.callbacks import Callback
  import torchbearer
  from torchbearer.metrics import Metric
label_desc: Use image node_id 11 for calling the TimerMetric obj's underlying member method code with example usage: obj.on_backward(state) without return types