code: def _fetch_attribute_specs_from_doc(cls, cls_in, attribute_name):
          
  
          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
docs: :type cls_in: type
          :type attribute_name: str
  
          :rtype: ValueSpecs