     assert List.insert_at([1, 2, 3], -10, 0) == [0, 1, 2, 3]
   end
 
-  test "replace at" do
+  test "replace_at/3" do
     assert List.replace_at([1, 2, 3], 0, 0) == [0, 2, 3]
     assert List.replace_at([1, 2, 3], 1, 0) == [1, 0, 3]
     assert List.replace_at([1, 2, 3], 2, 0) == [1, 2, 0]

  end

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

  test "partial application" do

    assert List.delete_at([1, 2, 3], -4) == [1, 2, 3]
  end

  test "to_string/1" do
    assert List.to_string([?æ, ?ß]) == "æß"
    assert List.to_string([?a, ?b, ?c]) == "abc"

