ImportError: No module named Cryptodome.Cipher
问题：
Traceback (most recent call last):
File "extract_bag.py", line 5, in <module>
import rosbag
File "/opt/ros/melodic/lib/python2.7/dist-packages/rosbag/__init__.py", line 33, in <module>
from .bag import Bag, Compression, ROSBagException, ROSBagFormatException, ROSBagUnindexedException
File "/opt/ros/melodic/lib/python2.7/dist-packages/rosbag/bag.py", line 53, in <module>
from Cryptodome.Cipher import AES
ImportError: No module named Cryptodome.Cipher
解决：
pip install pycryptodomex