python 3.x 不再提供raw_input(), 改为使用input(), print 改为 print(),
print 无括号形式不能再使用.
>>> raw_input('input name:');
Traceback (most recent call last):
File "<pyshell#3>", line 1, in <module>
raw_input('input name:');
NameError: name 'raw_input' is not defined
print 'hello world!'
SyntaxError: Missing parentheses in call to 'print'