Generate n-size running windows.

    Usage::

        >>> for i in running_windows([1, 2, 3, 4, 5], size=3):
        ...     print(i)
        [1, 2, 3]
        [2, 3, 4]
        [3, 4, 5]

def running_windows(iterable, size):
    """Generate n-size running windows.

    Usage::

        >>> for i in running_windows([1, 2, 3, 4, 5], size=3):
        ...     print(i)
        [1, 2, 3]
        [2, 3, 4]
        [3, 4, 5]
    """
    fifo = collections.deque(maxlen=size)
    for i in iterable:
        fifo.append(i)
        if len(fifo) == size:
            yield list(fifo)