he standard array indexing syntax.

    Examples
    --------
    >>> np.s_[2::2]
    slice(2, None, 2)
    >>> np.index_exp[2::2]
    (slice(2, None, 2),)

    >>> np.array([0, 1, 2, 3, 4])[np.s_[2::2]]
    array([2, 4])

    c