python dropwhile跳过开头的几行

   from itertools import dropwhile
 with open('/etc/passwd') as f:
 ...     for line in dropwhile(lambda line: line.startswith('#'), f):
 ...         print(line, end='')
 
 
 
   from itertools import islice
 items = ['a', 'b', 'c', 1, 4, 10, 15]
 for x in islice(items, 3, None):
 ...     print(x)
 ...
 1
 4
 10
 15