(function () {

  var libraryStorage = {};

  function librarySystem(libraryName, dependencyNames, callback) {

    // If using library
    if (arguments.length === 1) {
      return libraryStorage[libraryName];
    }

    // If creating library
    var dependencies = dependencyNames.map(function (dependencyName) {
      return libraryStorage[dependencyName];
    });

    libraryStorage[libraryName] = callback.apply(this, dependencies);

  }

  window.librarySystem = librarySystem;

  // Helper function used to reset libraryStorage after every test.
  function resetLibraryStorage() {
    libraryStorage = {};
  }

  window.resetLibraryStorage = resetLibraryStorage;

})();