Create middleware to handle responses

All the responses have the same code:

if (req.query.format === 'csv') {
      res.csv(result.data)
    } else if (req.query.format === 'xml') {
      res.set('Content-Type', 'text/xml')
      res.send(xml({
        result: result.data
      }))
    }
    else {
      res.json({
          result: result.data
      })
    }

This can be done by a custom middleware