基本就是第一层concatenate，第二层不concatenate.
相关论文：
Semi-Supervised Classification with Graph Convolutional Networks
Geometric deep learning on graphs and manifolds using mixture model CNNs
Convolutional Neural Networks on Graphs with Fast Localized Spectral Filtering
黄世宇/Shiyu Huang's Personal Page：https://huangshiyu13.github.io/
