code: function returnData (data, response) {
    if (typeof (response) === 'function') {
      return response(null, data)
    }
  
    if (!response.headersSent) {
      return response.status(200).end(JSON.stringify(data))
    }
  }
docs: In case database call return some data.
  If response parameter is a function consider this is a returnData callback function to call,
  else check if server response headers aren't send yet, and return response with status 200 and
  stringified data as content
  
  @param data - The server/database data
  @param response - The server response or returnData callback
  @returns {*} callback call or response with status 200 and associated data