code: def cross_origin_headers(self):
          
          if not self.is_cross_origin():
              return False
          # we allow everything
          self.send_header("Access-Control-Allow-Methods",
                           "GET, POST, PUT, DELETE, HEAD")
          allow_headers = _getheader(self.headers,
                                     'access-control-request-headers')
          if allow_headers is not None:
              self.send_header("Access-Control-Allow-Headers", allow_headers)
          self.send_header("Access-Control-Allow-Origin", "*")
          self.send_header("Access-Control-Allow-Credentials", "true")
          return allow_headers is not None
docs: Sends cross origin headers.