<SYSTEM_TASK:>
Solve the following problem using Python, implementing the functions described below, one line at a time
<END_TASK>
<USER_TASK:>
Description:
 def add_parser(self, name, func):
 """Register a new parser method with the name ``name``. ``func`` must receive the input value for an environment variable. """

        self.__parser_map__[name] = _func2method(func, method_name=name)
        return None