src/language-markdown/printer-markdown.js/printListItem
function printListItem(path, options, print, listPrefix) {
  const node = path.getValue();
  const prefix = node.checked === null ? "" : node.checked ? "[x] " : "[ ] ";
  return concat([
    prefix,
    printChildren(path, options, print, {
      processor: (childPath, index) => {
        if (index === 0 && childPath.getValue().type !== "list") {
          return align(" ".repeat(prefix.length), childPath.call(print));
        }

        const alignment = " ".repeat(
          clamp(options.tabWidth - listPrefix.length, 0, 3) // 4+ will cause indented code block
        );
        return concat([alignment, align(alignment, childPath.call(print))]);
      }
    })
  ]);
}