     assert List.update_at([1, 2, 3], -4, &(&1 + 1)) == [1, 2, 3]
   end
 
-  test "delete at" do
+  test "delete_at/2" do
     Enum.each [-1, 0, 1], fn i ->
       assert [] = List.delete_at([], i)
     end

    assert (&[&1, &2 | &3]).(1, 2, 3) == [1, 2 | 3]
  end

  test "wrap" do
    assert List.wrap([1, 2, 3]) == [1, 2, 3]
    assert List.wrap(1) == [1]
    assert List.wrap(nil) == []
  end

  test "flatten" do
    assert List.flatten([1, 2, 3]) == [1, 2, 3]
    assert List.flatten([1, [2], 3]) == [1, 2, 3]
    assert List.flatten([[1, [2], 3]]) == [1, 2, 3]

  end

  test "optional comma" do
    assert [1] == [1,]
    assert [1, 2, 3] == [1, 2, 3,]
  end

  test "partial application" do
