Eval.py Json import error

[mtkmark]

In eval.py got Some Error as the following ..
Any one knows how to solve it ?

python2.7 eval.py --model_path save/model.pth --infos_path save/infos_1.pkl --image_folder pic --num_images 1

===> ImportError: No module named _struct

==================
Traceback (most recent call last):
File "eval.py", line 5, in
import json
File "/usr/local/lib/python2.7/json/init.py", line 108, in
from .decoder import JSONDecoder
File "/usr/local/lib/python2.7/json/decoder.py", line 5, in
import struct
File "/usr/local/lib/python2.7/struct.py", line 1, in
from _struct import *
ImportError: No module named _struct