text: (req, res, postBack) => {
  
      const workspace = '<your workspace>';
      const index = '<index name>';
      const apiKey = '<api key here>';
      const interactionIdentifier = 'your-interaction-identifier';
  
      const search = req.text();
  
      const body = {
          search,
          searchFields: 'question',
          searchMode: 'any',
          // filter: 'topic eq '' + topic + ''',
          queryType: 'full',
          top: 3
      };
  
      postBack(interactionIdentifier, async () => {
          try {
  
              const options = {
                  uri: `https://${workspace}.search.windows.net/indexes/${index}/docs/search?api-version=2017-11-11`,
                  method: 'POST',
                  body,
                  headers: {
                      'Content-Type': 'application/json',
                      'api-key': apiKey,
                      'Cache-Control': 'no-cache'
                  },
                  json: true
              };
  
              const data = await request(options);
              return { data };
          } catch (err) {
              return { err };
          }
      });
  
  };
  