code: function _deepMerge(target, source) {
      Object.keys(source).forEach(function (key) {
          if (target[key] !== null && typeof target[key] === 'object' &&
              !Array.isArray(target[key])) {
              _deepMerge(target[key], source[key]);
          }
          else {
              target[key] = source[key];
          }
      });
  }
docs: Internal