node ../../bin/texts.js --from json --to xelatex
<<<
["text",
  ["numbered", { "level": 0 },
    ["plain", "First."]
  ],
  ["heading", { "level": -3 },
    ["plain", "Heading"]
  ]
]
>>>
\begin{enumerate}

\item First.

\end{enumerate}

\section{Heading}