def __enter__():
        """
        Enter a context using this PIDFile.

        Writes the PID file with the PID of the running process.

        @raise AlreadyRunningError: A process corresponding to the PID in this
            PID file is already running.
        """

        Enter a context using this PIDFile.

        Writes the PID file with the PID of the running process.

        @raise AlreadyRunningError: A process corresponding to the PID in this
            PID file is already running.
        
stackoverflow/venv/lib/python3.6/site-packages/twisted/application/runner/_pidfile.py