code: function outputDiagnostics(diagnostic) {
      var prefix = "  ";
      var output = prefix + "---\n";
      output += prefix + yaml.safeDump(diagnostic).split("\n").join("\n" + prefix);
      output += "...\n";
      return output;
  }
docs: Takes in a JavaScript object and outputs a TAP diagnostics string
  @param {object} diagnostic JavaScript object to be embedded as YAML into output.
  @returns {string} diagnostics string with YAML embedded - TAP version 13 compliant