OFCOURSE: A Multi-Agent Reinforcement Learning Environment for Order Fulfillment - Zhu, Yiheng; Zhan, Yang; Huang, Xuankun; Chen, Yuwei; Chen, yujie; Wei, Jiangwen; Feng, Wei; Zhou, Yinzhi; Hu, Haoyuan; Ye, Jieping (Advances in Neural Information Processing Systems, 2023)