```
% pandoc -f markdown -t native -s
---
header-includes: |
    \makeatletter
    \let\old@verbatim@font=\verbatim@font
    \def\verbatim@font{%
    \fontsize{10}{12}%
    \old@verbatim@font
    }
    \makeatother
...
^D
Pandoc
  Meta
    { unMeta =
        fromList
          [ ( "header-includes"
            , MetaBlocks
                [ RawBlock
                    (Format "tex")
                    "\\makeatletter\n\\let\\old@verbatim@font=\\verbatim@font\n\\def\\verbatim@font{%\n\\fontsize{10}{12}%\n\\old@verbatim@font\n}\n\\makeatother"
                ]
            )
          ]
    }
  []

```