def _request(self):
        """ Requests a checking of the editor content. """
        try:
            self.editor.toPlainText()
        except (TypeError, RuntimeError):
            return
        try:
            max_line_length = self.editor.modes.get(
                'RightMarginMode').position
        except KeyError:
            max_line_length = 79
        request_data = {
            'code': self.editor.toPlainText(),
            'path': self.editor.file.path,
            'encoding': self.editor.file.encoding,
            'ignore_rules': self.ignore_rules,
            'max_line_length': max_line_length,
        }
        try:
            self.editor.backend.send_request(
                self._worker, request_data, on_receive=self._on_work_finished)
            self._finished = False
        except NotRunning:
            # retry later
            QtCore.QTimer.singleShot(100, self._request)
Requests a checking of the editor content.