NOTE: Within Zorin OS: Start Software Updater > Settings... > Zorin Software > enable Source code. So that we can download Linux kernel source code.
-- get Linux source code, this expands to "./linux-hwe-7.0-7.0.0/"
sudo apt-get source linux-image-unsigned-7.0.0-28-generic
#sudo apt-get source linux-image-unsigned-7.0.0-30-generic