website/static/markdown.js/codeBlock
  function codeBlock(content, syntax) {
    var backtickSequences = content.match(/`+/g) || [];
    var longestBacktickSequenceLength = Math.max.apply(
      null,
      backtickSequences.map(function(backticks) {
        return backticks.length;
      })
    );
    var fenceLength = Math.max(3, longestBacktickSequenceLength + 1);
    var fence = Array(fenceLength + 1).join("`");
    return [fence + (syntax || ""), content, fence].join("\n");
  }