def isRunning():
        """
        Determine whether there is a running process corresponding to the PID
        in this PID file.

        @return: True if this PID file contains a PID and a process with that
        PID is currently running; false otherwise.
        @rtype: L{bool}

        @raise EnvironmentError: If this PID file cannot be read.
        @raise InvalidPIDFileError: If this PID file's content is invalid.
        @raise StalePIDFileError: If this PID file's content refers to a PID
            for which there is no corresponding running process.
        """

        Determine whether there is a running process corresponding to the PID
        in this PID file.

        @return: True if this PID file contains a PID and a process with that
        PID is currently running; false otherwise.
        @rtype: L{bool}

        @raise EnvironmentError: If this PID file cannot be read.
        @raise InvalidPIDFileError: If this PID file's content is invalid.
        @raise StalePIDFileError: If this PID file's content refers to a PID
            for which there is no corresponding running process.
        
stackoverflow/venv/lib/python3.6/site-packages/twisted/application/runner/_pidfile.py