python – ImportError：没有名为catkin_pkg.packages的模块

但我得到以下错误

Traceback (most recent call last):
  File "/opt/ros/kinetic/share/xacro/xacro.py",line 55,in <module>
    import xacro
  File "/opt/ros/kinetic/lib/python2.7/dist-packages/xacro/__init__.py",line 42,in <module>
    from roslaunch import substitution_args
  File "/opt/ros/kinetic/lib/python2.7/dist-packages/roslaunch/__init__.py",line 56,in <module>
    from .launch import ROSLaunchRunner
  File "/opt/ros/kinetic/lib/python2.7/dist-packages/roslaunch/launch.py",in <module>
    from roslaunch.nodeprocess import create_master_process,create_node_process
  File "/opt/ros/kinetic/lib/python2.7/dist-packages/roslaunch/nodeprocess.py",line 49,in <module>
    from roslaunch.node_args import create_local_process_args
  File "/opt/ros/kinetic/lib/python2.7/dist-packages/roslaunch/node_args.py",line 53,in <module>
    import roslib.packages
  File "/opt/ros/kinetic/lib/python2.7/dist-packages/roslib/__init__.py",line 54,in <module>
    import roslib.stacks
  File "/opt/ros/kinetic/lib/python2.7/dist-packages/roslib/stacks.py",line 46,in <module>
    import roslib.packages
  File "/opt/ros/kinetic/lib/python2.7/dist-packages/roslib/packages.py",in <module>
    from catkin.find_in_workspaces import find_in_workspaces as catkin_find
  File "/opt/ros/kinetic/lib/python2.7/dist-packages/catkin/find_in_workspaces.py",line 36,in <module>


from catkin_pkg.packages import find_packages
ImportError: No module named catkin_pkg.packages
while processing /opt/ros/kinetic/share/turtlebot_gazebo/launch/includes/kobuki.launch.xml:
Invalid <param> tag: Cannot load command parameter [robot_description]: command [/opt/ros/kinetic/share/xacro/xacro.py '/opt/ros/kinetic/share/turtlebot_description/robots/kobuki_hexagons_asus_xtion_pro.urdf.xacro'] returned with code [1].