human
Solve the following python programming problem given the following code:
def _install_restore_mode_child() : 
    global _mode_write_pipe 
    global _restore_mode_child_installed 
    if _restore_mode_child_installed : 
        return 
(mode_read_pipe, _mode_write_pipe) = os.pipe () 
    if (os.fork () == 0) : 
        os.close (parent_wait_lock) 
        PR_SET_PDEATHSIG = 1 
        libc = ctypes.cdll.LoadLibrary ('libc.so.6') 
        libc.prctl.argtypes = (ctypes.c_int, ctypes.c_ulong, ctypes.c_ulong, ctypes.c_ulong, ctypes.c_ulong) 
        libc.prctl (PR_SET_PDEATHSIG, signal.SIGHUP, 0, 0, 0) 
        def _sighup(signum, frame) : 
            parent_wait_lock.release () 
parent_wait_lock = threading.Lock () 
        parent_wait_lock.acquire () 
        signal.signal (signal.SIGHUP, _sighup) 
        packets = [] 
        buffer = asbytes ('') 
        while parent_wait_lock.locked () : 
            try : 
                data = os.read (mode_read_pipe, ModePacket.size) 
                buffer += data 
                while (len (buffer) >= ModePacket.size) : 
                    packet = ModePacket.decode (buffer [: ModePacket.size]) 
                    packets.append (packet) 
                    buffer = buffer [ModePacket.size :] 
except OSError : 
                pass 
for packet in packets : 
            packet.set () 
os._exit (0) 
else : 
        os.close (mode_read_pipe) 
        _restore_mode_child_installed = True 

    
    

    Fix the buggy line: os.close (parent_wait_lock)
assistant
#Here is Python program to fix the buggy line: os.

os.close (_mode_write_pipe)