设置visdom环境

D:\anaconda\envs\HSI_Classification-master\python.exe C:/Users/Administrator/Desktop/Hyperspectral-Classification-master/main.py
Computation on CPU
Traceback (most recent call last):
File "C:/Users/Administrator/Desktop/Hyperspectral-Classification-master/main.py", line 164, in
viz = visdom.Visdom(env=DATASET + ' ' + MODEL) # 设置visdom环境
TypeError: unsupported operand type(s) for +: 'NoneType' and 'str'
报错如下，麻烦解决一下，谢谢！