This component adds automatic line numbers to code blocks in Discourse, for blocks of two or more lines. Inline code, blocks of 1 line and onebox code blocks are not affected. The code language type (if specified) will be automatically displayed in the code block header, preceded by an optional title. Code block font size can also be changed in this component.
More info here: https://meta.discourse.org/t/code-block-line-numbers/330130
1 this code will
2 have line numbers
ths code will not
and neither will this code