class_docstr: A kqueue-based event loop for BSD/Mac systems.
code: def register(self, fd, events):
      if fd in self._active:
          raise IOError("fd %s already registered" % fd)
      self._control(fd, events, select.KQ_EV_ADD)
      self._active[fd] = events
  
file_path: catboost/contrib/python/tornado/tornado-4/tornado/platform/kqueue.py
imports: from __future__ import absolute_import, division, print_function
  import select
  from tornado.ioloop import IOLoop, PollIOLoop
label_desc: Use image node_id 4 for calling the _KQueue obj's underlying member method code with example usage: obj.register(fd, events) without return types