Returns
    -------
    taken : ExtensionArray
        The original `arr` with elements re-ordered appropriately

    Examples
    --------
    >>> arr = np.array(['a', 'b', 'c', 'd', 'e', 'f'])
    >>> _reorder_for_extension_array_stack(arr, 2, 3)
    array(['a', 'c', 'e', 'b', 'd', 'f'], dtype='<U1')

    >>> _reorder_for_extension_array_stack(arr, 3, 2)
    array(['a', 'd', 'b', 'e', 'c', 'f'], dtype='<U1')
    )