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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 increment_step_and_update_last_reward(self):
 """ Increment the step count of the trainer and Updates the last reward """

        if len(self.stats['Environment/Cumulative Reward']) > 0:
            mean_reward = np.mean(self.stats['Environment/Cumulative Reward'])
            self.policy.update_reward(mean_reward)
        self.policy.increment_step()
        self.step = self.policy.get_current_step()