enrich
stream,
nat
with
variables
lf : nat → list;
ii : nat → nat;
jj : nat → nat;
iigen : nat → nat → nat;
nfgen : nat → nat → elem;
nextl : nat × elem → list;
nextj : nat × elem → nat;
lfgen : nat → nat → list;
nf : nat → elem;
m : nat;
n : nat;
σ : stream;
a : elem;
end enrich