public function lookup_nonce($consumer, $token, $nonce, $timestamp)
	{
        $store = $this->getSubService(self::OPTION_NONCE_STORE);
        return $store->isValid($timestamp.'_'.$consumer->key.'_'.$nonce) ? null : true;
	}
public function lookup_nonce($consumer, $token, $nonce, $timestamp)
	{
        $store = $this->getSubService(self::OPTION_NONCE_STORE);
        return $store->isValid($timestamp.'_'.$consumer->key.'_'.$nonce) ? null : true;
	}
public function lookup_nonce ( $ consumer , $ token , $ nonce , $ timestamp ) { $ store = $ this -> getSubService ( self :: OPTION_NONCE_STORE ) ; return $ store -> isValid ( $ timestamp . '_' . $ consumer -> key . '_' . $ nonce ) ? null : true ; }
Should verify if a nonce has already been used
always return NULL, meaning that nonces can be reused

@access public
@author Joel Bout, <joel@taotesting.com>
@param OAuthConsumer $consumer
@param OAuthToken $token
@param string $nonce
@param string $timestamp
@return mixed
Should verify if a nonce has already been used always return NULL meaning that nonces can be reused