Checks if the the named location exists.

@param string $key
@return bool
483447
final public function offsetExists($key)
	{
		return	array_key_exists($key, $this->_stack) && isset($this->_stack[$key]);
	}
964085
public function exists($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 $data ? true : false;
    }
88651
public function exists($key)
	{
		if(empty($this->meta)) return false;
		return array_key_exists($key, $this->meta);
	}
923242
public function offsetExists($key)
    {
        return isset($this->container[$key]) || \array_key_exists($key, $this->container);
    }
334315
public function exists($key)
    {
        try {
            return $this->redis->exists($key);
        } catch (\RedisException $e) {
            die("Error!: " . $e->getMessage() . "<br/>");
        }
    }
439755
public function has(string $key): bool
    {
        $key = $this->getKey($key, true);
        return isset($this->headers[$key]);
    }
69348
public function has($key)
    {
        return $this->enabled && $this->filesystem->exists($this->cacheDir.$key);
    }
1141697
public function has($key)
    {
        if ($this->offsetExists($key) && (bool) $this->offsetGet($key)) {
            return true;
        }

        return false;
    }
618905
public function exists($storage_name, $key = null)
    {
        // No app found = false
        if (!isset($this->storage[$storage_name])) {
            return false;
        }

        // app found and no key requested? true
        if (!isset($key)) {
            return true;
        }

        // key requested and found? true
        return isset($this->storage[$storage_name]->{$key}) && !empty($this->storage[$storage_name]->{$key});
    }
720766
public function has($key)
    {
        // For performance, we can use isset,
        // but it will not match if value == 0
        return isset($this->values[$key]) || array_key_exists($key, $this->values);
    }
1039673
public function offsetExists($key)
    {
        if (isset($this->attributes[$key])) {
            return true;
        }

        return parent::offsetExists($key);
    }
113950
public function exists($key) {
        $key = $this->secureKey($key);
        
        if (isset($_SESSION[$key])) return true;
        
        return false;
    }
1032045
public function exists( $key ) {
		if ( ! $this->is_valid_session() ) {
			return false;
		}

		$key = $this->get_session_key( $key );
		if ( ! array_key_exists( $key, $_SESSION ) ) {
			return false;
		}

		return ! $this->_expired( $_SESSION[ $key ] );
	}
385444
public function __isset( $key )
    {
        // Delegate
        return ( array_key_exists( $key, $this->properties ) || isset( $this->storageOptions->$key ) );
    }
556221
public function has($key)
	{
		$this->memcached->get($key);
		if ($this->memcached->getResultCode() == Memcached::RES_NOTFOUND)
		{
			return false;
		}

		return true;
	}
441548
public function has(string $key): bool
    {
        if (!array_key_exists($key, $this->data)) {
            return false;
        }

        return true;
    }