src/language-js/embed.js/escapeBackticks
function escapeBackticks(doc) {
  return util.mapDoc(doc, currentDoc => {
    if (!currentDoc.parts) {
      return currentDoc;
    }

    const parts = [];

    currentDoc.parts.forEach(part => {
      if (typeof part === "string") {
        parts.push(part.replace(/`/g, "\\`"));
      } else {
        parts.push(part);
      }
    });

    return Object.assign({}, currentDoc, { parts });
  });
}