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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 learning_schedule() -> Callable: """ Returns a method that can be used in argument parsing to check that the argument is a valid learning rate schedule string. :return: A method that can be used as a type in argparse. """


    def parse(schedule_str):
        try:
            schedule = LearningRateSchedulerFixedStep.parse_schedule_str(schedule_str)
        except ValueError:
            raise argparse.ArgumentTypeError(
                "Learning rate schedule string should have form rate1:num_updates1[,rate2:num_updates2,...]")
        return schedule

    return parse