docs: function TAP13Producer() {
    /**
     * Writes the TAP version to reporter output stream.
     * @override
     */
    this.writeVersion = function() {
      println('TAP version 13');
    };
  
    /**
     * Writes that test failed to reporter output stream, with error formatting.
     * @override
     */
    this.writeFail = function(n, test, err) {
      TAPProducer.prototype.writeFail.call(this, n, test, err);
      var emitYamlBlock = err.message != null || err.stack != null;
      if (emitYamlBlock) {
        println(indent(1) + '---');
        if (err.message) {
          println(indent(2) + 'message: |-');
          println(err.message.replace(/^/gm, indent(3)));
        }
        if (err.stack) {
          println(indent(2) + 'stack: |-');
          println(err.stack.replace(/^/gm, indent(3)));
        }
        println(indent(1) + '...');
      }
    };
  
    function indent(level) {
      return Array(level + 1).join('  ');
    }
  }