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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 _register_parser(cls):
    '''class decorator to register msg parser'''
    assert cls.cls_msg_type is not None
    assert cls.cls_msg_type not in _MSG_PARSERS
    _MSG_PARSERS[cls.cls_msg_type] = cls.parser
    return cls