Support multiple line ranges in code block

[wenijinew]

For example, the code block has 10 lines, to highligh lines from 2-5, and 8-10.
I tried to set hl_lines="2-5" hl_lines="8-10", and only 8-10 are highlighed.

[facelessuser]

Did you check the documentation? It's covered there: https://facelessuser.github.io/pymdown-extensions/extensions/superfences/#highlighting-lines.

This is handled by a third party Markdown extension.