set_symbol_next  3865 src/alloc.c      set_symbol_next (val, NULL);
set_symbol_next  4926 src/lread.c      set_symbol_next (sym, SYMBOLP (*ptr) ? XSYMBOL (*ptr) : NULL);
set_symbol_next  5143 src/lread.c    	      set_symbol_next (tail, XSYMBOL (following)->u.s.next);