(Информация о версии неизвестна, возможно, только в SVN)
QuickHashStringIntHash::exists — This method checks whether a key is part of the hash
$key
)This method checks whether an entry with the provided key exists in the hash.
key
The key of the entry to check for whether it exists in the hash.
Returns TRUE when the entry was found, or FALSE when the entry is not
found.