src/language-markdown/mdx.js/esSyntax
function esSyntax() {
  const { Parser } = this;
  const { blockTokenizers, blockMethods, inlineTokenizers, inlineMethods } =
    Parser.prototype;

  blockTokenizers.esSyntax = tokenizeEsSyntax;
  inlineTokenizers.esComment = tokenizeEsComment;

  blockMethods.splice(blockMethods.indexOf("paragraph"), 0, "esSyntax");
  inlineMethods.splice(inlineMethods.indexOf("text"), 0, "esComment");
}