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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 is_possible_type( self, abstract_type: GraphQLAbstractType, possible_type: GraphQLObjectType ) -> bool: """Check whether a concrete type is possible for an abstract type."""

        possible_type_map = self._possible_type_map
        try:
            possible_type_names = possible_type_map[abstract_type.name]
        except KeyError:
            possible_types = self.get_possible_types(abstract_type)
            possible_type_names = {type_.name for type_ in possible_types}
            possible_type_map[abstract_type.name] = possible_type_names
        return possible_type.name in possible_type_names