Linux Panda3D, ImportError: No module named direct.directbase.DirectStart

What to do if you see the Error Message:
ImportError: No module named direct.directbase.DirectStart
This error means it couldn’t find the Python modules – please make sure you are running the correct version of Python (probably Python 3.7, that depends on the Panda3D version) and that the panda3d.pth is located inside the Python site- packages directory.

I got this problem during Panda3D Linux installation. Searching for panda3d.pth also
can not be found. So this is what i done to get the installation to work.
1. follow all steps in the Panda3D website
2. My system is Debian 10 64bit,
    a file panda3d1.10_1.10.0_amd64.deb created
3. After sudo dpkg -i panda3d1.10_1.10.0_amd64.deb
4. set $PYTHONPATH in ~/.bashrc
    export PYTHONPATH=/opt/pythonprj/panda3d/panda3d-src/built:$PYTHONPATH
*/ 'built' depends to the directory where one compile or execute this
    python makepanda/ --everything --installer
5. then run the environment by execute $ source ~/.bashrc or exit the terminal
    and relaunch, check with $ echo $PYTHONPATH, shud show the dir set at #4
$ python
Python 3.6.9 (default, Dec 19 2019, 01:20:01) 
[GCC 4.9.2] on linux
Type "help", "copyright", "credits" or "license" for more information.
>>> from direct.showbase.ShowBase import ShowBase

it works! ^^