append追加的使用

 #!/usr/bin/env python
 def fun(arg) :
     ret = []
     for i in range(len(arg)) :
         if i % 2 ==1 :
             ret.append(arg[i])
         else :
             pass
     return ret
 li = [11,22,33,44,55]
 r = fun(li)
 print(li)
 print(r)