def METHOD_NAME(self, element_id=None):
    if element_id is None:
        element_ids = self.element_id
        property_id = self.property_id
        i = None
    else:
        i = searchsorted(self.element_id, element_id)
        property_id = self.property_id[i]
    nsm = self.model.properties_shell.get_nonstructural_mass_by_property_id(property_id)
    return nsm