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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 add_input(self, in_name, type_or_parse=None):
 """ Declare a possible input """

        if type_or_parse is None:
            type_or_parse = GenericType()
        elif not isinstance(type_or_parse, GenericType) and callable(type_or_parse):
            type_or_parse = GenericType(parse=type_or_parse)
        elif not isinstance(type_or_parse, GenericType):
            raise ValueError("the given 'type_or_parse' is invalid")
        self._inputs[in_name] = type_or_parse