What's "OpenNMT-py/onmt/modules/Gate.py"?

I wanna use or implement sentinel gate which is introduced by “Knowing When to Look: Adaptive Attention via A Visual Sentinel for Image Captioning”[Lu+16].

I searched source code and found “OpenNMT-py/onmt/modules/Gate.py”.

Is that module based on [Lu+16]?

If not, Please tell me implementation of sentinel gate.