code: function (cb) {
              return this.get(1).chain(function (res) {
                  return isUndefinedOrNull(res) || res.length === 0;
              }.bind(this)).classic(cb);
          }
docs: Returns a promise that is resolved with true if no records exist in the dataset,
  false otherwise.
  @example
  
  // SELECT 1 FROM table LIMIT 1
  DB.from("table").isEmpty().chain(function(isEmpty){
  // isEmpty === false
  });
  
  @param {Function} [cb] a function to callback when action is done
  
  @return {comb.Promise} a promise that is resolved with a boolean indicating if the table is empty.