michael@0: // Map can take an argument that is an array of singleton arrays.
michael@0: 
michael@0: var arr = [["a"], ["b"], ["c"]];
michael@0: var m = Map(arr);
michael@0: assertEq(m.size, 3);
michael@0: for (var [k, _] of arr) {
michael@0:     assertEq(m.has(k), true);
michael@0:     assertEq(m.get(k), undefined);
michael@0: }