code: def _add_attr_property(self):
          
          property_ = property(self._getter, self._setter, None)
          # assign unconditionally to overwrite element name definition
          setattr(self._element_cls, self._prop_name, property_)
docs: Add a read/write ``{prop_name}`` property to the element class that
          returns the interpreted value of this attribute on access and changes
          the attribute value to its ST_* counterpart on assignment.