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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:
 async def commands(self):
 """Print a list with available commands."""

        _print_commands('Remote control', interface.RemoteControl)
        _print_commands('Metadata', interface.Metadata)
        _print_commands('Playing', interface.Playing)
        _print_commands('AirPlay', interface.AirPlay)
        _print_commands('Device', DeviceCommands)
        _print_commands('Global', self.__class__)

        return 0