docs: def parse_from_parent(
              self,
              parent,  # type: ET.Element
              state  # type: _ProcessorState
      ):
          # type: (...) -> Any
          """Parse the primitive value under the parent XML element."""
          element = parent.find(self.element_path)
  
          if element is None and self.required:
              state.raise_error(
                  MissingValue, 'Missing required element "{}"'.format(self.element_path)
              )
          elif element is not None:
              return self.parse_at_element(element, state)
  
          return _hooks_apply_after_parse(self._hooks, state, self._default)