function hasClient($clientName)
    {
        if (! isset($this->clients[$clientName]) ) {
            // Lookup for lazy client options
            try {
                $exists = true;
                $this->getClient($clientName);
            } catch (\Exception $e) {
                $exists = false;
            }

            return $exists;
        }

        $exists = array_key_exists($clientName, $this->lazyClientOptions);
        return $exists;
    }