code: function extend(dest, source) {
      dest = dest || {};
      source = source || {};
  
      var result = clone(dest);
      for (var key in source) {
          if (source.hasOwnProperty(key)) {
              result[key] = source[key];
          }
      }
      return result;
  }
docs: Extend the destination object with the given source
  @param {Object} dest the object to be extended
  @param {Object} source the source object
  @return {Object} the extended object