How to get all RethinkDB table keys and sub-keys (this version does not work recursively)

rethinkdb_table_keys.js

r.db('test').table('test')
  .concatMap(function(doc) {
    return doc.keys().map(function(tlKey) {
      return r.branch(doc(tlKey).typeOf().eq('OBJECT'), 
        doc(tlKey).keys().map(function(name){ return r.expr(tlKey).add('.').add(name);}), 
        tlKey);
    });
}).distinct()
/**
 * For object
 * { 
 *   id: 1,
 *   username: 'Jhonka',
 *   email: 'a@b.c',
 *   address: { street: 'Lorem', city: 'Ipsum' }
 * }
 * 
 * the output would be
 * [
 *   'id',
 *   'username',
 *   'email',
 *   [
 *     'address.street',
 *     'address.city'
 *   ]
 * ]
 */