fix nth

stdlib/stdlib.lsp

@@ -46,7 +46,7 @@
 (defun third (l) (index l 2))
 (defun fourth (l) (index l 3))
 (defun fifth (l) (index l 4))
-(defun nth (i l) (index l i))
+(defun nth (i l) (index l (- i 1))
 
 ; return 1 when list contains item otherwise 0
 (defun member (lst itm)