def METHOD_NAME(self,
                 uid: Union[UUID, str, LinkByUID, GEMDMaterialSpec]
                 ) -> Iterator[MaterialRun]:
    """
    Get the material runs using the specified material spec.
    Parameters
    ----------
    uid: Union[UUID, str, LinkByUID, GEMDMaterialSpec]
        A representation of the material spec whose material run usages are to be located.
    Returns
    -------
    Iterator[MaterialRun]
        The material runs using the specified material spec.
    """
    return self._get_relation('material-specs', uid=uid)