count expressions in python code, not including comment lines

code_count.py

#!/usr/bin/env python
# Copyright 2015 Paul Brewer
# This file is open source software
# License: The MIT License

import re
import sys 

if len(sys.argv)!=3:
    print 'Usage: '
    print ' python ./code_count.py /path/to/code.py "expression()" '
    print "   searches for and counts an expression in python code"
    print "   not including comments" # like this one
    print " returns integer count of lines containing the expression "
    sys.exit(-1);  

(scriptname, codefname, keyword) = sys.argv 

code_and_comment_lines = [] 

with open(codefname,'r') as codefile:
    code_and_comment_lines = codefile.readlines()

comment_regex = '(#.*$)'
comment_regex_c = re.compile(comment_regex)

codelines = [comment_regex_c.sub("", l) for l in code_and_comment_lines]

print sum((l.count(keyword) for l in codelines))