def process_pid(self):
if self.sprocess:<EOL><INDENT>return self.sprocess.pid<EOL><DEDENT>return -<NUM_LIT:1><EOL>
\
        when we are restarting, we want to keep sending heart beat, so any other single-beat
        node will not pick it up.
        hence we need a process-id as an identifier - even for a short period of time.
        :return: