code: function reverse(collection) {
      if (typeof collection === 'string') {
          return collection.split('').reverse().join('');
      }
      if(_.isArray(collection)){
          return collection.concat().reverse();
      }
      return collection;
  }
docs: reverse an array or a string
  
  {{ 'abc' | reverse }} => 'cba'
  {{ [1,2,3] | reverse }} => [3,2,1]