`lset=``=``list_1``list_2``...`procedureReturns true iff every LIST_I is set-equal to LIST_I+1, using = for the element-equality procedure. "Set-equal" simply means that LIST_I is a subset of LIST_I+1, and LIST_I+1 is a subset of LIST_I. The = procedure's first argument is an element of LIST_I; its second is an element of LIST_I+1.

(lset= eq? '(b e a) '(a e b) '(e e b a)) => #t (lset= eq?) => #t ; Trivial cases (lset= eq? '(a)) => #t