title: How do I return a List from Tornado?
body: <p>I'm trying to to get tornado to return a list.</p>
  
  <pre><code>@tornado.gen.coroutine
  @tornado.web.asynchronous
  def get(self, param):
  
      ...
      someList = [bla,bla,bla]
  
      self.finish(someList)
  </code></pre>
  
  <p>but whenever I do I get</p>
  
  <pre><code>HTTPRequest(protocol='http', host='tornado', method='GET', uri='/orders/submitted', version='HTTP/1.0', remote_ip='127.0.0.1', headers={'Accept-Language': 'en-US,en;q=0.8', 'Accept-Encoding': 'gzip,deflate,sdch', 'Host': 'tornado', 'Accept': 'application/json, text/plain, */*', 'User-Agent': 'Mozilla/5.0 (Macintosh; Intel Mac OS X 10_7_5) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/32.0.1700.107 Safari/537.36', 'Connection': 'close', 'Referer': 'admin/', 'Pragma': 'no-cache', 'Cache-Control': 'no-cache', 'Cookie': 'login="dHJ1ZQ==|1392074972|f4942e30293413717b380d1f362dd549548c404d"'})
  Traceback (most recent call last):
    File "/Users/ruahman/swipe-tech-apps/rpm-tornado/env/lib/python2.7/site-packages/tornado/web.py", line 1221, in _when_complete
      if result.result() is not None:
    File "/Users/ruahman/swipe-tech-apps/rpm-tornado/env/lib/python2.7/site-packages/tornado/concurrent.py", line 129, in result
      raise_exc_info(self.__exc_info)
    File "/Users/ruahman/swipe-tech-apps/rpm-tornado/env/lib/python2.7/site-packages/tornado/stack_context.py", line 302, in wrapped
      ret = fn(*args, **kwargs)
    File "/Users/ruahman/swipe-tech-apps/rpm-tornado/env/lib/python2.7/site-packages/tornado/gen.py", line 574, in inner
      self.set_result(key, result)
    File "/Users/ruahman/swipe-tech-apps/rpm-tornado/env/lib/python2.7/site-packages/tornado/gen.py", line 500, in set_result
      self.run()
    File "/Users/ruahman/swipe-tech-apps/rpm-tornado/env/lib/python2.7/site-packages/tornado/gen.py", line 531, in run
      yielded = self.gen.send(next)
    File "/Users/ruahman/swipe-tech-apps/rpm-tornado/fabfile/server/request_handlers/orders.py", line 26, in get
      self.finish((u"hi",))
    File "/Users/ruahman/swipe-tech-apps/rpm-tornado/env/lib/python2.7/site-packages/tornado/web.py", line 810, in finish
      self.write(chunk)
    File "/Users/ruahman/swipe-tech-apps/rpm-tornado/env/lib/python2.7/site-packages/tornado/web.py", line 610, in write
      chunk = utf8(chunk)
    File "/Users/ruahman/swipe-tech-apps/rpm-tornado/env/lib/python2.7/site-packages/tornado/escape.py", line 203, in utf8
      "Expected bytes, unicode, or None; got %r" % type(value)
  TypeError: Expected bytes, unicode, or None; got &lt;type 'tuple'&gt;
  ERROR:tornado.access:500 GET /orders/submitted (127.0.0.1) 8424.93ms
  </code></pre>
  
  <p>I don't have this problem when I return a dictionary.  it only happens when I return array.
  yes I could embed the list in a object but I prefer the result to be an array.</p>