function lookupAnimations(classes) {
      classes = isArray(classes) ? classes : classes.split(' ');
      var matches = [], flagMap = {};
      for (var i = 0; i < classes.length; i++) {
        var klass = classes[i],
            animationFactory = $animateProvider.$$registeredAnimations[klass];
        if (animationFactory && !flagMap[klass]) {
          matches.push($injector.get(animationFactory));
          flagMap[klass] = true;
        }
      }
      return matches;
    }
@ngdoc function
@name pascalprecht.translate.$translate#fallbackLanguage
@methodOf pascalprecht.translate.$translate

@description
Returns the language key for the fallback languages or sets a new fallback stack.
It is recommended to call this before {@link pascalprecht.translate.$translateProvider#preferredLanguage preferredLanguage()}.

@param {string=} langKey language String or Array of fallback languages to be used (to change stack at runtime)

@return {string||array} fallback language key