src/language-js/embed.js/transformCssDoc
function transformCssDoc(quasisDoc, path, print) {
  const parentNode = path.getValue();

  const isEmpty =
    parentNode.quasis.length === 1 && !parentNode.quasis[0].value.raw.trim();
  if (isEmpty) {
    return "``";
  }

  const expressionDocs = parentNode.expressions
    ? path.map(print, "expressions")
    : [];
  const newDoc = replacePlaceholders(quasisDoc, expressionDocs);
  /* istanbul ignore if */
  if (!newDoc) {
    throw new Error("Couldn't insert all the expressions");
  }
  return concat([
    "`",
    indent(concat([hardline, docUtils.stripTrailingHardline(newDoc)])),
    softline,
    "`"
  ]);
}