code: def _load_form_data(self):
          
          # abort early if we have already consumed the stream
          if "form" in self.__dict__:
              return
  
          _assert_not_shallow(self)
  
          if self.want_form_data_parsed:
              content_type = self.environ.get("CONTENT_TYPE", "")
              content_length = get_content_length(self.environ)
              mimetype, options = parse_options_header(content_type)
              parser = self.make_form_data_parser()
              data = parser.parse(
                  self._get_stream_for_parsing(), mimetype, content_length, options
              )
          else:
              data = (
                  self.stream,
                  self.parameter_storage_class(),
                  self.parameter_storage_class(),
              )
  
          # inject the values into the instance dict so that we bypass
          # our cached_property non-data descriptor.
          d = self.__dict__
          d["stream"], d["form"], d["files"] = data
docs: Method used internally to retrieve submitted data.  After calling
          this sets `form` and `files` on the request object to multi dicts
          filled with the incoming form data.  As a matter of fact the input
          stream will be empty afterwards.  You can also call this method to
          force the parsing of the form data.
  
          .. versionadded:: 0.8