def invokeAgent(query, session_id, enable_trace=False, session_state=dict()):
    end_session:bool = False
    
    # invoke the agent API
    agentResponse = bedrock_agent_runtime_client.invoke_agent(
        inputText=query,
        agentId=agent_id,
        agentAliasId=alias_id, 
        sessionId=session_id,
        enableTrace=enable_trace, 
        endSession= end_session,
        sessionState=session_state
    )
    
    if enable_trace:
        logger.info(pprint.pprint(agentResponse))
    
    event_stream = agentResponse['completion']
    try:
        agent_answer = ""
        for event in event_stream:        
            if 'chunk' in event:
                data = event['chunk']['bytes']
                chunk_text = data.decode('utf8')
                agent_answer += chunk_text

                if enable_trace:
                    logger.info(f"Chunk received ->\n{chunk_text}")
            elif 'trace' in event:
                if enable_trace:
                    logger.info(json.dumps(event['trace'], indent=2, cls=DateTimeEncoder))
            else:
                raise Exception("unexpected event.", event)

            if enable_trace:
                logger.info(f"Final answer ->\n{agent_answer}")
            
            return agent_answer
    except Exception as e:
        raise Exception("unexpected event.", e)