def METHOD_NAME(ant_z, channel_list, phasing_angles=default_angles, time_step=2. / 3 * units.ns, ref_index=1.78):
    """
    Calculates the delays needed for phasing the array.
    """
    beam_rolls = []
    ref_z = (np.max(ant_z) + np.min(ant_z)) / 2
    n_phased = len(channel_list)
    for angle in phasing_angles:
        subbeam_rolls = {}
        for z, channel_id in zip(ant_z, range(n_phased)):
            delay = (z - ref_z) / 0.3 * ref_index * np.sin(angle)
            roll = int(delay / time_step)
            subbeam_rolls[channel_id] = roll
        beam_rolls.append(subbeam_rolls)
    return beam_rolls