gensym definition library
/jen'sim/ (From the MacLISP
for "generated symbol") To invent a new name for something temporary, in such a way that the name is almost certainly not in conflict with one already in use.
The canonical form of a gensym is "Gnnnn" where nnnn represents a number; any LISP hacker
would recognise G0093 (for example) as a gensym. Gensymmed names are useful for storing or uniquely identifying crufties.