et from *iterable*.
The amount by which the `i`-th item in each tuple is offset is given by
the `i`-th item in *offsets*.

    >>> list(stagger([0, 1, 2, 3]))
    [(None, 0, 1), (0, 1, 2), (1, 2, 3)]
    >>> list(stagger(range(8), offsets=(0, 2, 4)))
    [(0, 2, 4), (1, 3, 5), (2, 4, 6), (3, 5, 7)]

By default, the sequence will end when the final element of a tuple is the
last item in the iterable. To continue until the first element of a tuple
is the last item in the iterable, set *longest* to ``True``::

    >>> list(stagger([0, 1, 2, 3], longest=True))
    [(None, 0, 1), (0, 1, 2), (1, 2, 3), (2, 3, None), (3, None, None)]

By default, ``None`` will be used to replace offsets beyond the end of the
sequence. Specify *fillvalue* to use some other value.

)