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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 on_parent_exit(signame):
 """ Return a function to be run in a child process which will trigger SIGNAME to be sent when the parent process dies """

    signum = getattr(signal, signame)
    def set_parent_exit_signal():
        # http://linux.die.net/man/2/prctl
        result = cdll['libc.so.6'].prctl(PR_SET_PDEATHSIG, signum)
        if result != 0:
            raise PrCtlError('prctl failed with error code %s' % result)
    return set_parent_exit_signal