TypeError: 'NoneType' object is not callable

[Jovian-wang]

Traceback (most recent call last):
File "C:/Users/DELL/Desktop/Super-Resolution-Images-master/main.py", line 41, in
for p in path():
TypeError: 'NoneType' object is not callable。In the main.py
I cannot to solve, Can you tell me how to settle it, thank so so much！