def METHOD_NAME(states):
    """
    Returns the absolute phase picked up by the first eigenstate in the Z
    basis. Note that this phase calculation is specific due to a trick
    used in this model where two different scenarios of the same state are
    compared.
    """
    phases = np.zeros(len(states))
    for i in range(len(states)):
        phase_a = np.arctan2(float(np.imag(states[i][0])),
                             float(np.real(states[i][0])))
        phases[i] = phase_a
    return phases