code: def on_epoch_begin(self, epoch_number, logs):
      self.constant_metric.value = (
          self.values[epoch_number - 1]
          if epoch_number < len(self.values)
          else self.values[-1]
      )
  
imports: from poutyne import Callback
label_desc: Use image node_id 2 for calling the ConstantMetricCallback obj's underlying member method code with example usage: obj.on_epoch_begin(epoch_number, logs) without return types