class_docstr: Schedules the given callback to be called once.
  
  The callback is called once, after callback_time milliseconds.
  
  `start` must be called after the DelayedCallback is created.
  
  The timeout is calculated from when `start` is called.
class_docstr_tok: ["Schedules","the","given","callback","to","be","called","once",".","The","callback","is","called","once",",","after","callback_time","milliseconds",".","`","start","`","must","be","called","after","the","DelayedCallback","is","created",".","The","timeout","is","calculated","from","when","`","start","`","is","called","."]
code: def __init__(self, callback, callback_time, io_loop=None):
      # PeriodicCallback require callback_time to be positive
      warnings.warn(
          """DelayedCallback is deprecated.
          Use loop.add_timeout instead.""",
          DeprecationWarning,
      )
      callback_time = max(callback_time, 1e-3)
      super(DelayedCallback, self).__init__(
          callback, callback_time, io_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 1 to create a new DelayedCallback object from inherited base classes: PeriodicCallback with example: obj = DelayedCallback(callback, callback_time, io_loop)