learn python the hard way 第三版是否不适用于 Python 2.7 版本？

为什么用notepad++运行以下代码时出错，
显示IndentationError: expected an indented block ，
它停留在第三行里，我百度过，听说与空格有关，
百思不得其解，遂请教于诸君。
# this one is like your scripts with argv
def print_two(*args):
arg1 , arg2 = args
print "arg1: %r, arg2: %r" % (arg1, arg2)
# ok, that *args is actually pointless, we can just do this
def print_two_again(arg1, arg2):
print "arg1: %r, arg2: %r" % (arg1, arg2)
# this just takes one argument
def print_one(arg1):
print "arg1: %r" % arg1
# this one takes no arguments
def print_none():
print "I got nothin'."
print_two("Zed","Shaw")
print_two_again("Zed","Shaw")
print_one("First!")
print_none()