class_docstr: Returns ForwardMsgs from our MessageCache
code: def set_default_headers(self):
      if allow_cross_origin_requests():
          self.set_header("Access-Control-Allow-Origin", "*")
  
imports: import os
  import tornado.web
  from streamlit import config, file_util
  from streamlit.logger import get_logger
  from streamlit.runtime.runtime_util import serialize_forward_msg
  from streamlit.web.server.server_util import emit_endpoint_deprecation_notice
label_desc: Use image node_id 2 for calling the MessageCacheHandler obj's underlying member method code with example usage: obj.set_default_headers() without return types