using System;

using System.Collections.Generic;

using System.Threading.Tasks;

public class Sample {

    public string ConnectionString;

    private Messenger _messenger = new Messenger();

    public void setExpired(string code) {

        var da = new DataAccess(ConnectionString);

        da.SetAsync(code, "E");

        _messenger.PublishEvent($"Set code {code} as Expired");

    }

}

​

public class DataAccess : IDisposable {

    public DataAccess(string connString) {

     // ...

    }

    // ...SetAsync method

}

​

public class Messenger() {

 // ...

}