Python : Determine last modified time of a web page

last-modified.py

#!/usr/bin/python2.7
import requests
import sys
from urlparse import urlparse 

#This will return last modified time of given web page url
def get_last_modified(url):
	result = urlparse(url)
	if True if [result.scheme, result.netloc, result.path] else False:
		header = requests.head(url).headers
		if 'Last-Modified' in header:
			return header['Last-Modified']
		print "Data is not available"
		return -1
	else:
		return -1
#Demonstration of function call
if __name__ == '__main__':
	try:
		url = sys.argv[1]
		print get_last_modified(url)
	except Exception as e:
		print "Please provide proper url as a first argument."