fixed submit answers

agentcourse_unit4/api/submit_answers_response.py

@@ -1,3 +1,4 @@
+
 class SubmitAnswersResponse:
     def __init__(self, username: str, score: int, correct_count: int, total_attempted: int, message: str, timestamp: str):
         self.username = username
@@ -9,10 +10,10 @@ class SubmitAnswersResponse:
 
 def to_submit_answers_response(json_data) -> SubmitAnswersResponse:
     return SubmitAnswersResponse(
-        username=json_data['username'] | '<unknown>',
-        score=json_data['score'] | 0,
-        correct_count=json_data['correct_count'] | 0,
-        total_attempted=json_data['total_attempted'] | 0,
-        message=json_data['message'] | 'No message received.',
-        timestamp=json_data['timestamp'] | '<unknown>'
+        username=json_data['username'] or '<unknown>',
+        score=json_data['score'] or 0,
+        correct_count=json_data['correct_count'] or 0,
+        total_attempted=json_data['total_attempted'] or 0,
+        message=json_data['message'] or 'No message received.',
+        timestamp=json_data['timestamp'] or '<unknown>'
     )