def METHOD_NAME(self) -> str:
    if self._unit_names == "":  # Ansys UnitSystem
        unit_system_strings = dpf.Operator("unit_system_strings")
        unit_system_strings.connect(0, self._ID)
        return unit_system_strings.get_output(0, str)
    else:  # Custom UnitSystem
        return self._unit_names