def METHOD_NAME():
    wcs = WCS(naxis=4)
    wcs.wcs.pc = np.zeros([4, 4])
    np.fill_diagonal(wcs.wcs.pc, np.arange(1, 5))
    pc = wcs.wcs.pc  # for later use below
    dropped = drop_axis(wcs, 0)
    assert np.all(dropped.wcs.get_pc().diagonal() == np.array([2, 3, 4]))
    dropped = drop_axis(wcs, 1)
    assert np.all(dropped.wcs.get_pc().diagonal() == np.array([1, 3, 4]))
    dropped = drop_axis(wcs, 2)
    assert np.all(dropped.wcs.get_pc().diagonal() == np.array([1, 2, 4]))
    dropped = drop_axis(wcs, 3)
    assert np.all(dropped.wcs.get_pc().diagonal() == np.array([1, 2, 3]))
    wcs = WCS(naxis=4)
    wcs.wcs.cd = pc
    dropped = drop_axis(wcs, 0)
    assert np.all(dropped.wcs.get_pc().diagonal() == np.array([2, 3, 4]))
    dropped = drop_axis(wcs, 1)
    assert np.all(dropped.wcs.get_pc().diagonal() == np.array([1, 3, 4]))
    dropped = drop_axis(wcs, 2)
    assert np.all(dropped.wcs.get_pc().diagonal() == np.array([1, 2, 4]))
    dropped = drop_axis(wcs, 3)
    assert np.all(dropped.wcs.get_pc().diagonal() == np.array([1, 2, 3]))