1. IndentationError: expected an indented block
------缩进问题
>>> for i in ['1','2','3','4']:
... t = s + i
File "<stdin>", line 2
t = s + i
^
IndentationError: expected an indented block
修改后
>>> for i in ['1','2','3','4']:
... t = s + i
... print t
...
string1
string2
string3
string4
