"""A page that echoes the Referrer header value via BroadcastChannel.
"""
def main(request, response):
referrer = request.headers.get(b"referer")
uid = request.GET.first(b"uid")
if referrer is None:
referrer = b"(none)"
html = u'''
Echo referrer
'''
return (200, [("Content-Type", b"text/html")],
html % (uid.decode("utf-8"), referrer.decode("utf-8")))