code: def call_at(self, when, callback, *args, **kwargs):
      # asyncio.call_at supports *args but not **kwargs, so bind them here.
      # We do not synchronize self.time and asyncio_loop.time, so
      # convert from absolute to relative.
      return self.asyncio_loop.call_later(
          max(0, when - self.time()),
          self._run_callback,
          functools.partial(
              stack_context.wrap(callback), *args, **kwargs
          ),
      )
  
imports: from __future__ import absolute_import, division, print_function
  import functools
  import tornado.concurrent
  from tornado.gen import convert_yielded
  from tornado.ioloop import IOLoop
  from tornado import stack_context
label_desc: Use image node_id 9 for calling the BaseAsyncIOLoop obj's underlying member method code with example usage: obj.call_at(when, callback) and returns: self