Python计算一个文件里字数的方法

from string import *
def countWords(s):
  words=split(s)
  return len(words)
  #returns the number of words
filename=open("welcome.txt",'r')
#open an file in reading mode
total_words=0
for line in filename:
  total_words=total_words + countWords(line)
  #counts the total words
print total_words