{lib, ...}: let
  merge = merge_list: let
    head_of_merge = builtins.head merge_list;
  in
    if builtins.isAttrs head_of_merge
    then
      builtins.zipAttrsWith (
        name: values: let
          head_value = builtins.head values;
        in
          if builtins.isString head_value
          then builtins.concatStringsSep "" values
          else if builtins.isList head_value
          then builtins.concatLists values
          else if builtins.isAttrs head_value
          then merge values
          else builtins.head values
      )
      merge_list
    else if builtins.isString head_of_merge
    then builtins.concatStringsSep "" merge_list
    else if builtins.isList head_of_merge
    then builtins.concatLists merge_list
    else builtins.head merge_list;

  # Tests
  ## Strings
  a = {
    a = ''
      This is some
    '';
  };
  b = {
    a = ''
      example text
    '';
  };
  c = {
    a = "(which is nice)";
  };
  ## Lists
  d = {
    a = ["element1" "element2"];
  };
  e = {
    a = [["elment3" "elemnt4"]];
  };
  f = {
    a = ["elemnt5"];
  };
  ## Pure strings
  g = "This";
  h = "is";
  i = "some example text";
  j = ''
    (with a newline)
  '';
  ## Pure lists
  k = ["element1"];
  l = ["element2" "element3"];
  m = ["element4"];

  ## Prepared tests
  tests = {
    tests = []; # Uncomment to actually run the tests
    test_strings = {
      expr = merge [a b c];
      expected = {a = "This is some\nexample text\n(which is nice)";};
    };
    test_lists = {
      expr = merge [d e f];
      expected = {a = ["element1" "element2" ["elment3" "elemnt4"] "elemnt5"];};
    };
    test_pure_strings = {
      expr = merge [g h i j];
      expected = "Thisissome example text(with a newline)\n";
    };
    test_pure_lists = {
      expr = merge [k l m];
      expected = ["element1" "element2" "element3" "element4"];
    };
  };
in {
  inherit merge;
  result = lib.debug.runTests tests;
}