if posn.Line > len(lines) || !strings.HasPrefix(lines[posn.Line-1], "type Int") {
			t.Fatalf("Object %v position %s does not contain its declaration",
				mathBigInt, posn)
		}
	})

	t.Run("LookupCustom", func(t *testing.T) {
		// TODO(mdempsky): Decide whether to remove this test, or to fix
		// support for it in unified IR. It's not clear that we actually
		// need to support importing "math/big" as "math/bigger", for