void RetryPoll(const std::string & upload_key,
               std::shared_ptr<FSM> fsmp,
               const boost::system::error_code & err)
{
    if (!err)
    {
        StartPoll(upload_key, *fsmp);
    }
}
 void operator()(
         Event const & evt,
         FSM & fsm,
         SourceState&,
         TargetState&
     )
 {
     StartPoll(evt.upload_key, fsm);
 }