code: function (property, callback, thisArg) {
          if(this.get(property)) {
            this.get(property).forEach(callback, thisArg);
          }
        }
docs: If the property is available, expects it to be an array and iterate over
  its elements using the callback.
  @param vertex {DataNode}
  @param callback {Function}
  @param thisArg {} Will be value of this inside the callback