protected JBIterable<T> _transform(JBIterable<?> original) {
      JBIterable<?> result = original;
      for (Function<Object, Object> f : _transformations()) {
        result = result.map(f);
      }
      //noinspection unchecked
      return (JBIterable<T>)result;
    }
protected JBIterable<T> _transform(JBIterable<?> original)