pdo:
PDO::ATTR_DEFAULT_FETCH_MODE
    
   PDO::FETCH_PROPS_LATE
    
   PDO::FETCH_KEY_PAIR
    
    
     Fetches a 2 column result set into an associated array. (Added in PHP 5.2.3)
    
   spl:
CachingIterator::FULL_CACHE
    
   CachingIterator::TOSTRING_USE_INNER
    
   SplFileObject::READ_AHEAD
    
   SplFileObject::READ_CSV
    
   SplFileObject::SKIP_EMPTY