secondItem.append(expected[1][1]);
input.append(firstItem);
input.append(secondItem);
DataBag result = function.exec(input); // run TOBAG on ((a,b),(c,d))
assertEquals("number of tuples in the bag", 2, result.size()); // we should have 2 tuples in the output bag
int position = 0;
for (Tuple t : result) {
assertEquals("number of items in tuple " + position, 2, t.size()); // each tuple should contain 2 items