Looking at discrete structures, there is an obvious tree we may form with a set of words. This might be called an index tree, but we don't want to jump the gun. Some things I did for the sake of depressing friends who got more depressed when I explained to them what I knew; which was around the time a couple of buildings fell down because someone flew an aeroplane into them or something. But some men you just can't reach.
So we'll call it an obvious tree. We also need to name a struct, obviously. The atoms of this struct include the parent file-address (fad). As we prefer not to call something nothing, and fads might be optional, we hereby announce the opt-fad: which is either in or out. Obviously, with a parent fad that is out, we are not alone.
printf("%s\n",*( (char**)0 ));