机器学习 | ModuleNotFoundError: No module named 'gym'，但是已经安装gym

## method one
# In your code file,add following:

import sys
sys.path.append('your gym folder')    # e.g. mine   sys.path.append('/home/eric/gym')

## method two
# In your bashrc or zshrc file,add following:
export GYM_PATH=/home/eric/gym:$GYM_PATH    # This is my folder location,replace yours