Determine whether a particular header exists

@param string $key The key to check for
@return bool
439755
public function has(string $key): bool
    {
        $key = $this->getKey($key, true);
        return isset($this->headers[$key]);
    }
300181
public function exists(string $key)
    {
        return $this->useRedis(function($resource, $redis) use($key){
            return $redis->hexists($this->getStoreKey(), $key);
        });
    }
551349
public function has(?string $key) : bool
    {
        return $key === null ? false : isset($this->themes[$key]);
    }
127667
public function has($key) {
        $key = $this->formatKey($key);
        return array_has($this->headers, $key);
    }
288391
public function has(string $key){
        $data   = $this->status() === self::ACTIVE
            ? $_SESSION : $this->finishedData;
        
        return array_key_exists($key, $data);
    }
1300431
public function has($key)
    {
        return (bool) $this->redis->exists($this->redis->prefix($key));
    }
619011
private static function keyExists($key)
    {
        $apiKeyCount = self::where('key', '=', $key)->limit(1)->count();

        if ($apiKeyCount > 0) return true;

        return false;
    }
1029588
protected function exists($key)
    {
        if ($this->enabled && opcache_is_script_cached($this->filePath($key))) {
            return true;
        }
        return file_exists($this->filePath($key));
    }
379742
public function exists(string $key) : bool
    {
        $this->checkCallback();
        return isset($this->members[$key]);
    }
469164
public function has(string $key): bool
    {
        if (strpos($key, '.') != false) {
            return $this->getNested($key) != null;
        }

        return array_key_exists($key, $this->settings);
    }
964085
public function exists($key)
    {
        if (null === $this->configs) {
            $this->loadConfigs();
        }

        return array_key_exists($key, $this->configs);
    }
376902
public function exists($key) {
        $key = $this->_encrypt($key);
        $data = $this->_memcached->get($key);
        
        return $data ? true : false;
    }
1349419
public function has($key)
    {
        return isset($this->data[$key]) || array_key_exists($key, $this->data);
    }
619117
public function exist($key) : bool
    {
        return $this->get($key, false) !== false
               && $this->get($key, true) !== true;
    }
602663
protected function hasKey($key)
    {
        return ($this->mode == self::MODE_INDEXED && $key == '') || \array_key_exists($key, $this->params);
    }
433328
public function has(string $key): bool
    {
        $key = $this->prepareKey($key);
        return Arr::has($this->properties, $key);
    }
381311
public function has($key){
        if($this->offsetExists($key) && (bool)$this->offsetGet($key)){
            return TRUE;
        }
        return FALSE;
    }