human
Solve the following python programming problem given the following code:
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.

    Based on https://gist.github.com/evansd/2346614
    ' 
    def noop() : 
        pass 
try : 
        libc = cdll ['libc.so.6'] 
except OSError : 
        return noop 
try : 
        prctl = libc.prctl 
except AttributeError : 
        return noop 
signum = getattr (signal, signame) 
    def set_parent_exit_signal() : 
        result = prctl (PR_SET_PDEATHSIG, signum) 
        if (result != 0) : 
            raise Exception (('prctl failed with error code %s' % result)) 
return <MASK> 
    
    Given the code above, what is a proper replacement for <MASK>? Choose among: prctl, signame, signum, noop, libc
assistant
#Here is a proper replacement for <MASK>.
def set_parent_exit_signal(