diff --git a/modules/fishnet/fishnet.py b/modules/fishnet/fishnet.py
index 7c0ba93..0155b05 100644
--- a/modules/fishnet/fishnet.py
+++ b/modules/fishnet/fishnet.py
@@ -1,16 +1,16 @@
 # -*- coding: utf-8 -*-
 
-from __future__ import print_function
 from __future__ import division
+from __future__ import print_function
 
-import json
-import time
 import contextlib
-import sys
+import ctypes
+import json
 import os
-import stat
 import platform
-import ctypes
+import stat
+import sys
+import time
 
 try:
     import httplib
@@ -260,6 +260,11 @@ def detect_cpu_capabilities():
     return modern, bmi2
 
 
+class ConfigError(Exception):
+    """Error in configuration."""
+    pass
+
+
 class HttpError(Exception):
     def __init__(self, status, reason, body):
         self.status = status