enrich cell-heap ,
list with
functions
ls : ref × list → heap → bool;
axioms
ls-base : ⊦ ls(r, []) = (emp ∧ ⌜r = null⌝ );
used for : s, ls;
ls-rec : ⊦ ls(r, a ' + x) = _∃ λ r0. r => a × r0 * ls(r0, x);
used for : s, ls;
end enrich