docs: function waitIdleTimeExpire(key, timeout) {
    return function(client) {
      var contains = true;
      t.sleepFor(200); // sleep required
      waitsFor(function() {
        client.containsKey(key).then(function(success) {
          contains = success;
        });
  
        return !contains;
      }, '`' + key + '` key should be expired', timeout);
  
      return client;
    }
  }