You are an expert in writing code in many different languages. Your goal is to perform code completion for the following code, keeping in mind the rest of the code and the file meta data.
    Metadata details:
    filename: cancel_wf.rs
    path of file: ./repos/sdk-core/tests/integ_tests/workflow_tests
    
    the code of the file until where you have to start completion: use std::time::Duration;
use temporal_client::WorkflowClientTrait;
use temporal_sdk::{WfContext, WfExitValue, WorkflowResult};
use temporal_sdk_core_protos::temporal::api::enums::v1::WorkflowExecutionStatus;
use temporal_sdk_core_test_utils::CoreWfStarter;

async fn cancelled_wf(ctx: WfContext) -> WorkflowResult<()> {
    let cancelled = tokio::select! {
        _ = ctx.timer(Duration::from_secs(500)) => false,
        
    
async fn cancel_during_timer() {
    let wf_name = "cancel_during_timer";
    let mut starter = CoreWfStarter::new(wf_name);
    starter.no_remote_activities();
    let mut worker = starter.worker().await;
    let client = starter.get_client().await;
    worker.register_wf(wf_name.to_string(), cancelled_wf);
    starter.start_with_worker(wf_name, &mut worker).await;
    let wf_id = starter.get_task_queue().to_string();

    let canceller = async {
        tokio::time::sleep(Duration::from_millis(500)).await;
        // Cancel the workflow externally
        client
            .cancel_workflow_execution(wf_id.clone(), None, "Dieee".to_string(), None)
            .await
            .unwrap();
    };

    let (_, res) = tokio::join!(canceller, worker.run_until_done());
    res.unwrap();
    let desc = client
        .describe_workflow_execution(wf_id, None)
        .await
        .unwrap();

    assert_eq!(
        desc.workflow_execution_info.unwrap().status,
        WorkflowExecutionStatus::Canceled as i32
    );
}