docs: function cloneById (v, k) {
      if (Array.isArray(v)) {
        let match = find(v, it => String(it[options.idField]) === String(k));
        return match? cloneDeep(match) : (options.keepOrig? k : null);
      } else {
        return String(v[options.idField]) === String(k)? cloneDeep(v) : (options.keepOrig? k : null);
      }
    }