Python Tornado: WSGI module missing?

I did a pip install tornado but I cannot run the following code because WSGI module is missing??

http://flask.pocoo.org/docs/deploying/wsgi-standalone/

from tornado.wsgi import WSGIContainer
from tornado.httpserver import HTTPServer
from tornado.ioloop import IOLoop
from myapp import app

http_server = HTTPServer(WSGIContainer(app))
http_server.listen(5000)
IOLoop.instance().start()