text: # Webhooks for external integrations.
  from typing import Any, Dict, Iterable, Optional, Text
  
  from django.http import HttpRequest, HttpResponse
  from django.utils.translation import ugettext as _
  
  from zerver.decorator import api_key_only_webhook_view
  from zerver.lib.actions import check_send_stream_message
  from zerver.lib.request import REQ, has_request_variables
  from zerver.lib.response import json_error, json_success
  from zerver.lib.validator import check_dict, check_string
  from zerver.models import UserProfile
  
  @api_key_only_webhook_view('Mention')
  @has_request_variables
  def api_mention_webhook(request: HttpRequest, user_profile: UserProfile,
                          payload: Dict[str, Iterable[Dict[str, Any]]] = REQ(argument_type='body'),
                          stream: Text = REQ(default='mention'),
                          topic: Text = REQ(default='news')) -> HttpResponse:
      title = payload["title"]
      source_url = payload["url"]
      description = payload["description"]
      # construct the body of the message
      body = '**[%s](%s)**:\n%s' % (title, source_url, description)
  
      # send the message
      check_send_stream_message(user_profile, request.client, stream, topic, body)
  
      return json_success()
  