[1.8.x] Removed comment from Form.changed_data; refs #24191

    def changed_data(self):

        if self._changed_data is None:

            self._changed_data = []

            # XXX: For now we're asking the individual fields whether or not the

            # data has changed. It would probably be more efficient to hash the

            # initial data, store it in a hidden field, and compare a hash of the

            # submitted data, but we'd need a way to easily get the string value

            # for a given field. Right now, that logic is embedded in the render

            # method of each widget.

            for name, field in self.fields.items():

                prefixed_name = self.add_prefix(name)

                data_value = field.widget.value_from_datadict(self.data, self.files, prefixed_name)