code: def headers(self) -> dict[str, str | list[str]]:
      return self._headers
  
imports: from __future__ import annotations
  import logging
  import weakref
  from typing import TYPE_CHECKING, Any, Awaitable, Callable, Iterable
  from tornado import gen
  from ..application.application import ServerContext, SessionContext
  from ..document import Document
  from ..protocol.exceptions import ProtocolError
  from ..util.token import get_token_payload
  from .session import ServerSession
label_desc: Use image node_id 4 for calling the _RequestProxy obj's underlying member method code with example usage: obj.headers() and returns: self