code: def write(self, chunk, callback=None):
      if self._expected_content_remaining is not None:
          self._expected_content_remaining -= len(chunk)
          if self._expected_content_remaining < 0:
              self._error = httputil.HTTPOutputError(
                  "Tried to write more data than Content-Length"
              )
              raise self._error
      self._write_buffer.append(chunk)
      if callback is not None:
          callback()
      return _dummy_future
  
imports: from __future__ import absolute_import, division, print_function
  import sys
  from io import BytesIO
  import tornado
  from tornado.concurrent import Future
  from tornado import escape
  from tornado import httputil
  from tornado.log import access_log
  from tornado import web
  from tornado.escape import native_str
  from tornado.util import unicode_type, PY3
label_desc: Use image node_id 4 for calling the _WSGIConnection obj's underlying member method code with example usage: obj.write(chunk, callback) and returns: _dummy_future