public function oddKey(array $storage)
    {
        return $this->filter($storage, function ($value, $key)
        {
            return $this->helper->math()->isOdd($key);
        });
    }
public function oddKey(array $storage)
    {
        return $this->filter($storage, function ($value, $key)
        {
            return $this->helper->math()->isOdd($key);
        });
    }
public function oddKey ( array $ storage ) { return $ this -> filter ( $ storage , function ( $ value , $ key ) { return $ this -> helper -> math ( ) -> isOdd ( $ key ) ; } ) ; }
0=>'', 2=> ''...

@param array $storage

@return array
0 = > 2 = > ...