protected function getKey(array $config)
    {
        if (!isset($config['key']) || !is_string($config['key'])) {
            throw new \DomainException(
                'key must reference a string',
                self::ERR_INVALID_KEY
            );
        }
        return $config['key'];
    }
protected function getKey(array $config)
    {
        if (!isset($config['key']) || !is_string($config['key'])) {
            throw new \DomainException(
                'key must reference a string',
                self::ERR_INVALID_KEY
            );
        }
        return $config['key'];
    }
protected function getKey ( array $ config ) { if ( ! isset ( $ config [ 'key' ] ) || ! is_string ( $ config [ 'key' ] ) ) { throw new \ DomainException ( 'key must reference a string' , self :: ERR_INVALID_KEY ) ; } return $ config [ 'key' ] ; }
Extracts a Google API key for interacting with the YouTube API from
configuration.

@param array $config
@return string
@throws \DomainException if key setting is invalid
Extracts a Google API key for interacting with the YouTube API from configuration .