public function exist($keyName) : bool
    {
        # double check
        return
            $this->get($keyName, true) !== true
            && $this->get($keyName, false) !== false;
    }
public function exist($keyName) : bool
    {
        # double check
        return
            $this->get($keyName, true) !== true
            && $this->get($keyName, false) !== false;
    }
public function exist ( $ keyName ) : bool { # double check return $ this -> get ( $ keyName , true ) !== true && $ this -> get ( $ keyName , false ) !== false ; }
Check whether Session is exists or not on segment

@param string $keyName
@return bool
Check whether Session is exists or not on segment