old_contents: var assign = require('lodash.assign');
  var testrunner = require('../lib/testrunner').testRunner;
  
  var es2015 = require('./es2015.json');
  var es2016 = require('./es2016.json');
  var es2017 = require('./es2017.json');
  
  function syntax() {
    var es2015Test = testrunner(es2015, 'es2015');
    var es2016Test = testrunner(es2016, 'es2015');
    var es2017Test = testrunner(es2017, 'es2015');
  
    var result = assign({
      es2015: es2015Test,
      es2016: es2016Test,
      es2017: es2017Test
    }, es2015Test, es2016Test, es2017Test);
  
    result.__all = es2015Test.__all && es2016Test.__all && es2017Test.__all;
  
    return result;
  }
  
  module.exports = { syntax: syntax };
  
new_contents: var testrunner = require('../lib/testrunner').testRunner;
  var assign = require('../lib/assign');
  
  var es2015 = require('./es2015.json');
  var es2016 = require('./es2016.json');
  var es2017 = require('./es2017.json');
  
  function syntax() {
    var es2015Test = testrunner(es2015, 'es2015');
    var es2016Test = testrunner(es2016, 'es2015');
    var es2017Test = testrunner(es2017, 'es2015');
  
    var result = assign({
      es2015: es2015Test,
      es2016: es2016Test,
      es2017: es2017Test
    }, es2015Test, es2016Test, es2017Test);
  
    result.__all = es2015Test.__all && es2016Test.__all && es2017Test.__all;
  
    return result;
  }
  
  module.exports = { syntax: syntax };
  
subject: Use new assign method instead of lodash