code: function expectText(fn, res) {
    bluebird.try(fn).then(result => {
      res.set('Content-Type', 'text/plain');
      res.send(result);
    }).catch(handleError(res));
  }
docs: Reusable code to return Text data, both for good results AND errors.
  
  Captures and hides appropriate errors.
  
  @param {function} fn
  @param {object} res