def writeRunningPID():
        """
        Store the PID of the current process in this PID file.

        @raise EnvironmentError: If this PID file cannot be written.
        """

        Store the PID of the current process in this PID file.

        @raise EnvironmentError: If this PID file cannot be written.
        
stackoverflow/venv/lib/python3.6/site-packages/twisted/application/runner/_pidfile.py