substrings and their positions in *seq*

    The items yielded will be a tuple of the form ``(substr, i, j)``, where
    ``substr == seq[i:j]``.

    This function only works for iterables that support slicing, such as
    ``str`` objects.

    >>> for item in substrings_indexes('more'):
    ...    print(item)
    ('m', 0, 1)
    ('o', 1, 2)
    ('r', 2, 3)
    ('e', 3, 4)
    ('mo', 0, 2)
    ('or', 1, 3)
    ('re', 2, 4)
    ('mor', 0, 3)
    ('ore', 1, 4)
    ('more', 0, 4)

    Set *reverse* to ``True`` to yield the same items in the opposite order.


    r-