code: function (identifier, values) {
              var self = this;
  
              return self.needByIdentifier(identifier)
                  .then(function (record) {
                      return self.update(
                          record.id,
                          values
                      ).then(function (records) {
                          return records[0];
                      });
                  });
          }
docs: Look up and update values by identifier - either the "id" or in the identifiers array.
  Returns a waterline (bluebird) promise with the record updated.
  Rejects the promise if the document was not found.
  
  @param {string} identifier
  @param {Object} values
  @returns {Deferred}