>>> from tornado.gen import coroutine
>>> from tornado.web import Application, RequestHandler
>>> from tornado_sqlalchemy import as_future, make_session_factory, SessionMixin
>>>
>>> factory = make_session_factory('postgres://user:password@host/database')
>>>
>>> class MyRequestHandler(RequestHandler, SessionMixin):
...     @coroutine
...     def get(self):
...         with self.make_session() as session:
...             count = yield as_future(session.query(UserModel).count)
...
...         self.write('{} users so far!'.format(count)
...
>>> app = Application(((r'/', MyRequestHandler),), session_factory=factory)