docs: def makeXsl(filename):
    """ Helper that creates a XSLT stylesheet """
    pkg = 'cnxml2html'
    package = ''.join(['.' + x for x in __name__.split('.')[:-1]])[1:]
    if package != '':
        pkg = package + '.' + pkg
    path = pkg_resources.resource_filename(pkg, filename)
    xml = etree.parse(path)
    return etree.XSLT(xml)