TYPE 
EquipDB = Cod -> Multiset;
Multiset = Cod -> Nat;
Cod = STR;
Nat = INT;
GG = Cod | Nat;
HH = A:GG B:GG;
ENDTYPE

FUNC  MsUnion (m:Multiset, n:Multiset) : Multiset
RETURNS  m\dom(n) + n\dom(m) + [x -> m[x] .+ n[x] | x <- dom(m) * dom(n)];

FUNC  MsMul (v:Nat ,m:Multiset) : Multiset
RETURNS   [x -> v .* m[x] | x <- dom(m)];

FUNC   X (e:Cod) : Multiset
RETURNS  Y(1,DB[e],DB,[])
STATE    DB <- DB;

FUNC   Y (n:Nat,r:Multiset,s:EquipDB,t:Multiset) : Multiset
RETURNS   if (r == []) 
          then t
          else  let ( e = choice(dom(r)), 
                      m = r[e] )
                in if ( s[e] == [] )
                   then  Y(n, r\{e}, s, MsUnion(t, MsMul(n, [e -> m])))
                   else  Y(n .* m, s[e], s, Y(n, r\{e}, s, t)) ;


DB <- ["aa" -> ["bb" -> 6, "cc" -> 3], "bb" -> ["cc" -> 4, "w" -> 1], "cc"
-> ["yy" -> 4], "w" -> [], "yy" -> []];