fun ander [] = true
  | ander (h::t) = h andalso ander t
  ;

fun spansv [] b test = (b,[])
  | spansv a b test = if test (hd a) then spansv (tl a) (b@[hd a]) test else (b,a)
  ;

fun span nil test = ([],[])
  | span ls test = spansv ls [] test
  ;

fun alternating_sum [] = 0
  | alternating_sum (h::t) = h - alternating_sum t
  ;

fun isEmpty [] = true
  | isEmpty stk = false
  ;

fun push x stk = x::stk;

fun pop (top::stk) = (stk,top);

fun multipush []  stk = stk
  | multipush lst stk = multipush (tl lst) (push (hd lst) stk)
  ;

fun multipopsv 0 stk sv = (stk,sv)
  | multipopsv n stk sv = multipopsv (n-1) (tl stk) ( sv@[hd stk] )
  ;

fun multipop n stk = multipopsv n stk [];