对python生成器特性使用的好例子

def (seq, size): 
    """
    Returns an iterator over a series of lists of length size from iterable.
        >>> list(group([1,2,3,4], 2))
        [[1, 2], [3, 4]]
        >>> list(group([1,2,3,4,5], 2))
        [[1, 2], [3, 4], [5]]
    """
    def take(seq, n):
        for i in xrange(n):
            yield seq.next() 
    if not hasattr(seq, 'next'):
         seq = iter(seq) 
    while True:  
        inger=take(seq, size) 
        x = list(inger) 
        if x: 
              yield x 
        else: 
              break