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Solve the following problem using Python, implementing the functions described below, one line at a time
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Description:
 def write_pid_file():
 """Write a file with the PID of this server instance. Call when setting up a command line testserver. """

    pidfile = os.path.basename(sys.argv[0])[:-3] + '.pid'  # strip .py, add .pid
    with open(pidfile, 'w') as fh:
        fh.write("%d\n" % os.getpid())
        fh.close()