function getEventData(options) {
    return {
      addClass: options.addClass,
      removeClass: options.removeClass,
      from: options.from,
      to: options.to
    };
  }
@ngdoc function
@name pascalprecht.translate.$translate#negotiateLocale
@methodOf pascalprecht.translate.$translate

@description
Returns a language key based on available languages and language aliases. If a
language key cannot be resolved, returns undefined.

If no or a falsy key is given, returns undefined.

@param {string} [key] Language key
@return {string|undefined} Language key or undefined if no language key is found.