def ellipsis_eqiv(key):
    """
    Returns whether *key* is a *tuple* of *Ellipsis* or equivalent *slice*s.
    """
    return isinstance(key, tuple) and all(
        k is Ellipsis or
        isinstance(k, slice) and (
            k.start in (None, 0) and
            k.stop in (None, -1) and
            k.step in (None, 1)
        )
        for k in key
    )