fix cli.py lint warning

cli.py

@@ -1,4 +1,14 @@
 #!/usr/bin/env python3
+"""
+BNG Blaster Control Socket Client
+
+Simple script to interact with the BNG Blaster
+control socket JSON RPC API. 
+
+Christian Giese, January 2021
+
+Copyright (C) 2020-2021, RtBrick, Inc.
+"""
 import sys
 import socket
 import os
@@ -21,11 +31,13 @@ Examples:
     sys.exit(1)
 
 def error(*args, **kwargs):
+    """print error and exit"""
     print(*args, file=sys.stderr, **kwargs)
     sys.exit(1)
 
 
 def main():
+    """main function"""
     request = {}
     if(len(sys.argv)) < 3:
         usage()
@@ -34,15 +46,18 @@ def main():
 
     request["command"] = sys.argv[2]
     if(len(sys.argv)) > 4:
-        request["arguments"] = {} 
+        request["arguments"] = {}
         for i in range(3, len(sys.argv), 2):
             arg = sys.argv[i+1]
-            try: 
+            try:
+                # integer arguments like "session-id 1"
                 request["arguments"][sys.argv[i]] = int(arg)
             except:
                 try:
+                    # list arguments like "sessions [1,2]""
                     request["arguments"][sys.argv[i]] = ast.literal_eval(arg)
-                except: 
+                except:
+                    # string arguments like "group 239.0.0.1"
                     request["arguments"][sys.argv[i]] = arg
         #print(json.dumps(request).encode('utf-8'))
     if os.path.exists(socket_path):