def _fetch_attribute_specs_from_doc(cls, cls_in, attribute_name):
        """
        :type cls_in: type
        :type attribute_name: str

        :rtype: ValueSpecs
        """

        pattern = cls._TEMPLATE_PATTERN_PARAM_TYPES.format(attribute_name)
        match = re.search(pattern, cls_in.__doc__)

        if match is not None:
            return ValueSpecs(
                cls._fetch_name(match),
                ValueTypes(
                    cls._fetch_type_main(cls_in, match),
                    cls._fetch_type_sub(cls_in, match)
                )
            )
        else:
            return None
:type cls_in: type
        :type attribute_name: str

        :rtype: ValueSpecs