code: function isActive() {
      try {
        var key = '___session is active___';
        return session.get(key) || session.set(key, true);
      } catch (err) {
        return false;
      }
    }
docs: Set a heuristic for determining if the session
  is actually active.
  
  @return {Boolean} Returns `true` if session is active
  @api private