Declare that other types may be converted to this property type.

        Args:
            tp (Property) :
                A type that may be converted automatically to this property
                type.

            converter (callable) :
                A function accepting ``value`` to perform conversion of the
                value to this property type.

        Returns:
            self

def accepts(self, tp, converter):
        ''' Declare that other types may be converted to this property type.

        Args:
            tp (Property) :
                A type that may be converted automatically to this property
                type.

            converter (callable) :
                A function accepting ``value`` to perform conversion of the
                value to this property type.

        Returns:
            self

        '''

        tp = ParameterizedProperty._validate_type_param(tp)
        self.alternatives.append((tp, converter))
        return self