def METHOD_NAME():
    path = join(data_dir("structure"), "1l2y.mmtf")
    mmtf_file = mmtf.MMTFFile.read(path)
    stack1 = mmtf.get_structure(
        mmtf_file,
        extra_fields=[
            "atom_id", "b_factor", "occupancy", "charge"
        ]
    )
    mmtf_file == mmtf.MMTFFile()
    mmtf.set_structure(mmtf_file, stack1)
    stack2 = mmtf.get_structure(
        mmtf_file,
        extra_fields=[
            "atom_id", "b_factor", "occupancy", "charge"
        ]
    )
    assert stack1.atom_id.tolist() == stack2.atom_id.tolist()
    assert stack1.b_factor.tolist() == approx(stack2.b_factor.tolist())
    assert stack1.occupancy.tolist() == approx(stack2.occupancy.tolist())
    assert stack1.charge.tolist() == stack2.charge.tolist()