ImportError: cannot import name 'Log' from 'rosgraph_msgs.msg'

[zkailinzhang]

import bagpy

ImportError Traceback (most recent call last) in ----> 1 import bagpy

---> 49 from .client import spin, myargv, init_node,
50 get_published_topics,
51 wait_for_message, \

~//lib/python3.7/site-packages/rospy/client.py in 52 import roslib 53 ---> 54 import rospy.core 55 from rospy.core import logwarn, loginfo, logerr, logdebug 56 import rospy.exceptions

~//lib/python3.7/site-packages/rospy/core.py in 73 from rospy.impl.validators import ParameterInvalid 74 ---> 75 from rosgraph_msgs.msg import Log 76 from functools import partial 77

ImportError: cannot import name 'Log' from 'rosgraph_msgs.msg' (/opt/ros/dashing/lib/python3.6/site-packages/rosgraph_msgs/msg/init.py)