How to use the gramex.service.threadpool.submit function in gramex

def delete(self):
        if self.driver_name != 'sqlalchemy':
            raise NotImplementedError('driver=%s is not supported yet.' % self.driver_name)
        kwargs = {'_wheres': self.getq('where')}
        if self.thread:
            self.result = yield gramex.service.threadpool.submit(self._sqlalchemy_delete, **kwargs)
        else:
            self.result = self._sqlalchemy_delete(**kwargs)
        self.renderdata()

def post(self):
        if self.driver_name != 'sqlalchemy':
            raise NotImplementedError('driver=%s is not supported yet.' % self.driver_name)
        kwargs = {'_vals': self.getq('val', [])}
        if self.thread:
            self.result = yield gramex.service.threadpool.submit(self._sqlalchemy_post, **kwargs)
        else:
            self.result = self._sqlalchemy_post(**kwargs)
        self.renderdata()

def post(self, *args, **kwargs):
        if self.redirects:
            self.save_redirect_page()
        upload = yield gramex.service.threadpool.submit(self.uploader.addfiles, self)
        delete = yield gramex.service.threadpool.submit(self.uploader.deletefiles, self)
        self.set_header('Content-Type', 'application/json')
        self.write(json.dumps({'upload': upload, 'delete': delete},
                              ensure_ascii=True, separators=(',', ':')))
        if self.redirects:
            self.redirect_next()

def sendmail(handler):
    mailer = gramex.service.email[handler.get_argument('from')]
    folder = os.path.dirname(os.path.abspath(__file__))
    gramex.service.threadpool.submit(
        mailer.mail,
        to=handler.get_argument('to'),
        subject=handler.get_argument('subject', 'Gramex guide test'),
        html='<p>This is a <strong>test email</strong> from ' +
             '<a href="https://learn.gramener.com/guide/email/mail">Gramex</a></p>' +
             '<p><img src="cid:kitten"></p>',
        body='This is a plain text email from Gramex for non-HTML browsers',
        attachments=[os.path.join(folder, 'README.md')],
        images={'kitten': os.path.join(folder, 'kitten.jpg')},
    )
    return 'Mail is being sent. <a href=".">Back to email app</a>'

def post(self, *args, **kwargs):
        if self.redirects:
            self.save_redirect_page()
        upload = yield gramex.service.threadpool.submit(self.uploader.addfiles, self)
        delete = yield gramex.service.threadpool.submit(self.uploader.deletefiles, self)
        self.set_header('Content-Type', 'application/json')
        self.write(json.dumps({'upload': upload, 'delete': delete},
                              ensure_ascii=True, separators=(',', ':')))
        if self.redirects:
            self.redirect_next()

def get(self):
        limit = int(self.getq('limit', [100])[0])
        if isinstance(self.query, dict):
            # Bind all queries and run them in parallel
            args = {
                key: self.getq(key, [''])[0]
                for name, query in self.query.items()
                for key, _bindparams in query._bindparams.items()
            }
            stmts = AttrDict([
                (key, q.bindparams(**{k: v for k, v in args.items() if k in q._bindparams}))
                for key, q in self.query.items()
            ])
            if self.thread:
                futures = AttrDict([
                    (key, gramex.service.threadpool.submit(self.run, stmt, limit))
                    for key, stmt in stmts.items()
                ])
                self.result = AttrDict()
                for key, future in futures.items():
                    self.result[key] = yield future
            else:
                self.result = AttrDict([
                    (key, self.run(stmt, limit)) for key, stmt in stmts.items()])
            self.renderdatas()
        else:
            # Bind query and run it
            args = {key: self.getq(key, [''])[0] for key in self.query._bindparams}
            stmt = self.query.bindparams(**{k: v for k, v in args.items()
                                            if k in self.query._bindparams})
            if self.thread:
                self.result = yield gramex.service.threadpool.submit(self.run, stmt, limit)

for key, stmt in stmts.items()
                ])
                self.result = AttrDict()
                for key, future in futures.items():
                    self.result[key] = yield future
            else:
                self.result = AttrDict([
                    (key, self.run(stmt, limit)) for key, stmt in stmts.items()])
            self.renderdatas()
        else:
            # Bind query and run it
            args = {key: self.getq(key, [''])[0] for key in self.query._bindparams}
            stmt = self.query.bindparams(**{k: v for k, v in args.items()
                                            if k in self.query._bindparams})
            if self.thread:
                self.result = yield gramex.service.threadpool.submit(self.run, stmt, limit)
            else:
                self.result = self.run(stmt, limit)
            self.renderdata()

def languagetool(handler, *args, **kwargs):
    import gramex
    merge(kwargs, _languagetool['defaults'], mode='setdefault')
    yield gramex.service.threadpool.submit(languagetool_download)
    if not handler:
        lang = kwargs.get('lang', 'en-us')
        q = kwargs.get('q', '')
    else:
        lang = handler.get_argument('lang', 'en-us')
        q = handler.get_argument('q', '')
    result = yield languagetoolrequest(q, lang, **kwargs)
    errors = json.loads(result.decode('utf8'))['matches']
    if errors:
        result = {
            "errors": errors,
        }
        corrected = list(q)
        d_offset = 0  # difference in the offset caused by the correction
        for error in errors:
            # only accept the first replacement for an error