code: def write_fileno(self):
      return self.writer.fileno()
  
file_path: catboost/contrib/python/tornado/tornado-4/tornado/platform/posix.py
imports: from __future__ import absolute_import, division, print_function
  import fcntl
  import os
  from tornado.platform import common, interface
label_desc: Use image node_id 3 for calling the Waker obj's underlying member method code with example usage: obj.write_fileno() and returns: self