def print_matchs(matchtext):
  print "looking for",matchtext
  while True:
    line = (yield)
    #用 yield语句并以表达式（yield)的形式创建协程
    if matchtext in line:
      print line
> matcher = print_matchs('python')
> matcher.next()
looking for python
> matcher.send('hello python')#看生成器那片，关于send()跟next()的区别
hello python
> matcher.send('test')
> matcher.send('python is cool')
python is cool
>matcher.close()