# coding: utf-8

import tornado
import tornado.web
from tornado import ioloop, gen, httpclient
from tornado.web import RequestHandler

class Holder(object):
    pass

holder = Holder()

@gen.engine
def outside_function(callback, value):
    holder.value = value
    yield gen.Task(httpclient.AsyncHTTPClient().fetch, 'https://www.google.com')
    callback(value)

class MasterHandler(RequestHandler):

    @gen.coroutine
    def get(self):
        holder.value = self.get_argument('value', 'default')
        yield gen.Task(outside_function, value=holder.value)
        self.finish(str(holder.value))

urls = [
    (r'/', MasterHandler),
]

app = tornado.web.Application(urls)
app.listen(8000)
ioloop.IOLoop().instance().start()