ModuleNotFoundError: No module named 'rclyp'

edit

 #!/usr/bin/env python3

import rclyp

from rclyp.node import Node

def main(args = None):
    rclyp.init(args = args)
    node = Node("py_test")
    node.get_logger().info("Hello ROS2")
    rclyp.shutdown()

if __name__ == "__main__":
    main()

Hi I am new at ROS2 trying to use this code but my terminal says :

> user@user-VirtualBox:~/ros2_ws/src/my_py_pkg/my_py_pkg$
> ./my_first_node.py  Traceback (most
> recent call last):   File
> "/home/user/ros2_ws/src/my_py_pkg/my_py_pkg/./my_first_node.py", line 3, in <module>
>     import rclyp ModuleNotFoundError: No module named 'rclyp'

I have tried this link but It doesn't look like same error like I got.