add Connection::flush();

src/Connection.php

@@ -186,6 +186,15 @@ protected function _getResponse() {
 		return $response;
 	}
 
+	/**
+	 * Wait until all statements received response.
+	 */
+	public function flush(){
+		while(!empty($this->_statements)){
+			$this->_getResponse();
+		}
+	}
+
 	/**
 	 * @return Connection\Node
 	 */

src/Response/Result.php

@@ -42,7 +42,7 @@ protected function _readBytesAndConvertToType($type){
 		$length = unpack('N', substr($this->data, $this->offset, 4))[1];
 		$this->offset += 4;
 
-		if ($length === 4294967295)
+		if ($length === 0xffffffff)
 			return null;
 
 		// do not use $this->read() for performance