```
% pandoc -f latex -t native
\newcommand{\mycolor}{red}

\includegraphics[width=17cm]{\mycolor /header}
Magnificent \mycolor{} header.
^D
[ Para
  [ Image
    ( "", [], [ ( "width", "17cm" ) ] )
    [ Str "image" ]
    ( "red/header", "" )
  , SoftBreak
  , Str "Magnificent"
  , Space
  , Str "red"
  , Space
  , Str "header."
  ]
]
```