Problem with KeyError: 'TASK_ROOT_DIR'

[lylyjy]

When I run main.py, it occurs :

TASK_ROOT_DIR=os.environ['TASK_ROOT_DIR']
raise KeyError(key) from None
KeyError: 'TASK_ROOT_DIR'

from modified_LQR_env import *

ModuleNotFoundError: No module named 'modified_LQR_env'

What should I do?Thanks!