def pid(self):
        """
        The integer PID of the subprocess or None.
        """
        pf = self.path('cmd.pid')
        if not os.path.exists(pf):
            return None
        with open(pf, 'r') as f:
            return int(f.read())
def pid ( self ) : pf = self . path ( 'cmd.pid' ) if not os . path . exists ( pf ) : return None with open ( pf , 'r' ) as f : return int ( f . read ( ) )
The integer PID of the subprocess or None.