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Solve the following problem using Python, implementing the functions described below, one line at a time
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Description:
 def on_step_end(self, step, logs):
 """ Update statistics of episode after each step """

        episode = logs['episode']
        self.observations[episode].append(logs['observation'])
        self.rewards[episode].append(logs['reward'])
        self.actions[episode].append(logs['action'])
        self.metrics[episode].append(logs['metrics'])
        self.step += 1