class_docstr: Wraps an `HTTPMessageDelegate` to decode ``Content-Encoding: gzip``.
      
class_docstr_tok: ["Wraps","an","`","HTTPMessageDelegate","`","to","decode","``","Content-Encoding",":","gzip","``","."]
code: def headers_received(self, start_line, headers):
      if headers.get("Content-Encoding") == "gzip":
          self._decompressor = GzipDecompressor()
          # Downstream delegates will only see uncompressed data,
          # so rename the content-encoding header.
          # (but note that curl_httpclient doesn't do this).
          headers.add(
              "X-Consumed-Content-Encoding", headers["Content-Encoding"]
          )
          del headers["Content-Encoding"]
      return self._delegate.headers_received(start_line, headers)
  
imports: from __future__ import absolute_import, division, print_function
  import re
  from tornado.concurrent import Future
  from tornado.escape import native_str, utf8
  from tornado import gen
  from tornado import httputil
  from tornado import iostream
  from tornado.log import gen_log, app_log
  from tornado import stack_context
  from tornado.util import GzipDecompressor, PY3
label_desc: Use image node_id 2 for calling the _GzipMessageDelegate obj's underlying member method code with example usage: obj.headers_received(start_line, headers) and returns: self