class_docstr: ZMQ subclass of tornado's IOLoop
  
  Minor modifications, so that .current/.instance return self
class_docstr_tok: ["ZMQ","subclass","of","tornado","'s","IOLoop","Minor","modifications",",","so","that",".current\/.instance","return","self"]
docstr: Returns a global `IOLoop` instance.
  
  Most applications have a single, global `IOLoop` running on the
  main thread.  Use this method to get this instance from
  another thread.  To get the current thread's `IOLoop`, use `current()`.
docstr_tok: ["Returns","a","global","`","IOLoop","`","instance",".","Most","applications","have","a","single",",","global","`","IOLoop","`","running","on","the","main","thread",".","Use","this","method","to","get","this","instance","from","another","thread",".","To","get","the","current","thread","'s","`","IOLoop","`",",","use","`","current","(",")","`","."]
code: def instance(cls, *args, **kwargs):
      """Returns a global `IOLoop` instance.
  
      Most applications have a single, global `IOLoop` running on the
      main thread.  Use this method to get this instance from
      another thread.  To get the current thread's `IOLoop`, use `current()`.
      """
      # install ZMQIOLoop as the active IOLoop implementation
      # when using tornado 3
      if tornado_version >= (3,):
          PollIOLoop.configure(cls)
      loop = PollIOLoop.instance(*args, **kwargs)
      if not isinstance(loop, cls):
          warnings.warn(
              "IOLoop.current expected instance of %r, got %r"
              % (cls, loop),
              RuntimeWarning,
              stacklevel=2,
          )
      return loop
  
imports: from __future__ import absolute_import, division, with_statement
  import os
  import time
  import warnings
  from zmq import Poller, POLLIN, POLLOUT, POLLERR, ZMQError, ETERM
  from .minitornado.ioloop import PollIOLoop, PeriodicCallback
  from .minitornado.log import gen_log
label_desc: Use image node_id 2 for calling the ZMQIOLoop obj's underlying member method code with example usage: obj.instance(cls) and returns: loop