https://www.bilibili.com/video/BV1zt411G7Vn?p=10&spm_id_from=pageDriver

rosrun learning_topic velocity_publisher.py 

给的错误反馈是:

Traceback (most recent call last):
  File "/home/wxx/catkin_ws/devel/lib/learning_topic/velocity_publisher.py", line 10, in <module>
    import rospy
  File "/opt/ros/noetic/lib/python3/dist-packages/rospy/__init__.py", line 47, in <module>
    from std_msgs.msg import Header
  File "/opt/ros/noetic/lib/python3/dist-packages/std_msgs/msg/__init__.py", line 1, in <module>
    from ._Bool import *
  File "/opt/ros/noetic/lib/python3/dist-packages/std_msgs/msg/_Bool.py", line 6, in <module>
    import genpy
  File "/opt/ros/noetic/lib/python3/dist-packages/genpy/__init__.py", line 34, in <module>
    from . message import Message, SerializationError, DeserializationError, MessageException, struct_I
  File "/opt/ros/noetic/lib/python3/dist-packages/genpy/message.py", line 48, in <module>
    import yaml
ImportError: No module named yaml

求大佬解答