protected function arrayKey($key, $prefix)
    {
        $arrayKey = substr($key, strlen($prefix)+1);
        return is_bool($arrayKey) ? '' : $arrayKey;
    }
protected function arrayKey($key, $prefix)
    {
        $arrayKey = substr($key, strlen($prefix)+1);
        return is_bool($arrayKey) ? '' : $arrayKey;
    }
protected function arrayKey ( $ key , $ prefix ) { $ arrayKey = substr ( $ key , strlen ( $ prefix ) + 1 ) ; return is_bool ( $ arrayKey ) ? '' : $ arrayKey ; }
Return the array key inside a cached array.

@param string $key
@param string $prefix

@return string
Return the array key inside a cached array .