def METHOD_NAME(run_number):
    """Check that the eigenvectors of UT_U are maximally entangled."""
    unitary = random_unitary(2)
    states, eigvals = calculate_psi(unitary)
    np.testing.assert_allclose(np.abs(eigvals), np.ones(4))
    for state in states.T:
        np.testing.assert_allclose(purity(state), 0.5)