diff --git a/ch4/service/ch4_service_py/ch4_service_py/self_service.py b/ch4/service/ch4_service_py/ch4_service_py/self_service.py
index 787368d..6b68de5 100644
--- a/ch4/service/ch4_service_py/ch4_service_py/self_service.py
+++ b/ch4/service/ch4_service_py/ch4_service_py/self_service.py
@@ -15,9 +15,9 @@
 import rclpy
 import rclpy.executors
 
-from rclpy.node import Node
 from rcl_interfaces.msg import Parameter
 from rcl_interfaces.srv import GetParameters
+from rclpy.node import Node
 
 
 class ServerNode(Node):