code: function makeNext(browser) {
          return function next(code) {
              exitCode += code;
              currentRun++;
              if (code === 0) {
                  // Add Browser name here
                  console.log(browser + ' success');
              } else {
                  console.log(browser + ' fail');
              }
              if (currentRun == numberOfRuns) {
                  process.exit(exitCode);
              }
          };
      }
docs: Helper to make the main thread wait for the children to finish before deciding on its own error code.