code: function _assign(target) {
      var sources = [], len = arguments.length - 1;
      while ( len-- > 0 ) sources[ len ] = arguments[ len + 1 ];
  
  
      sources.forEach(function (source) {
          Object.keys(source || {}).forEach(
              function (key) { return target[key] = source[key]; }
          );
      });
  
      return target;
  }
docs: Object.assign() polyfill.