LXML simple renderer

>This program will take an .xml, .xsl file from the command line and perform a transform. It defaults to a .html file output but you can add a third argument to have the end anything you want.

#!/usr/bin/env python
import sys
from lxml import etree
"""
xsltransform.py
./xsltransform.py [xmlfile] [xslfile] [optional ext]

Transfroms an xml file via, xsl.
"""
if len(sys.argv)<4:
	ext ='html'
else:
	ext = sys.argv[3]

#load xml doc and parse
xml_doc = open(sys.argv[1],'r')
xml_tree = etree.parse(xml_doc)

#load xsl doc parse and create a transform
xsl_doc = open(sys.argv[2],'r')
xslt_tree = etree.parse(xsl_doc)
transform = etree.XSLT(xslt_tree)

#write the output to a file.
out = open('out.%s'%ext,'w')
out.write(str(transform(xml_tree)))