class_docstr: A callback for recording GPU power draw (watts) on epoch begin and end.
  
  Example use:
  
  power_draw = PowerDraw()
  
  model.fit(...callbacks=[power_draw]...)
  
  history = talos.utils.power_draw_append(history, power_draw)
code: def on_train_begin(self, logs={}):
      self.log = {}
      self.log["epoch_begin"] = []
      self.log["epoch_end"] = []
      self.log["seconds"] = []
  
imports: from tensorflow.keras.callbacks import Callback
label_desc: Use image node_id 2 for calling the PowerDraw obj's underlying member method code with example usage: obj.on_train_begin(logs) without return types