def METHOD_NAME(tmpdir):
    xyz = np.array(np.random.randn(500, 10, 3), dtype=np.float32)
    fn = '{}/x.binpos'.format(tmpdir)
    with BINPOSTrajectoryFile(fn, 'w') as f:
        f.write(xyz[0:250])
        f.write(xyz[250:])
    xyz2 = BINPOSTrajectoryFile(fn).read()
    assert eq(xyz, xyz2)