ws.py: make url an argument

ws.py

-import time
+import argparse
 import json
+import time
 
 from websocket import create_connection
 
-url = "ws://[2a11:9ac0:d::1]:9002"
+parser = argparse.ArgumentParser(description='Connect to a lteue websocket to perform some testing.')
+parser.add_argument('url', help='url of the websocket in the form ws://[XXX]:XXX (eg "ws://[2a11:9ac0:d::1]:9002")')
+args = parser.parse_args()
 
 class UeError(Exception):
     pass
@@ -45,7 +48,7 @@ def power_off(ws, ue_id):
 try:
 
     try:
-        ws = create_connection(url)
+        ws = create_connection(args.url)
     except ConnectionRefusedError:
         raise UeError("Couldn't connect to remote API")