def METHOD_NAME(self):
    """Write a multi-model, multi-chain mmCIF file."""
    pdb_struct = self.pdb_parser.get_structure(
        "1SSU_mod_pdb", self.mmcif_multimodel_pdb_file
    )
    mmcif_struct = self.mmcif_parser.get_structure(
        "1SSU_mod_mmcif", self.mmcif_multimodel_mmcif_file
    )
    io = MMCIFIO()
    for struct in [pdb_struct, mmcif_struct]:
        self.io.set_structure(struct)
        filenumber, filename = tempfile.mkstemp()
        os.close(filenumber)
        try:
            self.io.save(filename)
            struct_in = self.mmcif_parser.get_structure("1SSU_mod_in", filename)
            self.assertEqual(len(struct_in), 2)
            self.assertEqual(len(struct_in[1]), 2)
            self.assertAlmostEqual(
                struct_in[1]["B"][1]["N"].get_coord()[0], 6.259, 3
            )
        finally:
            os.remove(filename)