It returns list sorted in zigzag.

zigzag_sorted.py

def zigzag_sorted(iterable, key=None):
    """It returns list sorted in zigzag.
    :rtype: generator object (iterator)

    >>> list(zigzag_sorted([1, 2, 3, 4, 5, 6, 7]))
    [1, 7, 2, 6, 3, 5, 4]
    """
    i = 0
    l = sorted(iterable, key=key)
    n = len(l)
    if not n:
        return
    for j in range(n):
        yield l[i]
        if j % 2 == 0:
            i = -i - 1
        else:
            i = abs(i)