class Program
{
    static void Main(string[] args)
    {
        KA().Wait();
    }

    static async Task KA()
    {
        await WriteToPipe();
        Console.WriteLine("YES!");
    }

    private static async Task WriteToPipe()
    {
        StreamReader reader = new StreamReader(new MemoryStream());
        string line = await reader.ReadLineAsync();
        Console.WriteLine("Readed!");
    }
}

turns into...:
  internal class Program
  {
    public Program()
    {
      base.\u002Ector();
    }

    private static void Main(string[] args)
    {
      Program.KA().Wait();
    }

    private static Task KA()
    {
      Program.\u003CKA\u003Ed__1 stateMachine;
      stateMachine.\u003C\u003Et__builder = AsyncTaskMethodBuilder.Create();
      stateMachine.\u003C\u003E1__state = -1;
      stateMachine.\u003C\u003Et__builder.Start<Program.\u003CKA\u003Ed__1>(ref stateMachine);
      return stateMachine.\u003C\u003Et__builder.Task;
    }

    private static Task WriteToPipe()
    {
      Program.\u003CWriteToPipe\u003Ed__1 stateMachine;
      stateMachine.\u003C\u003Et__builder = AsyncTaskMethodBuilder.Create();
      stateMachine.\u003C\u003E1__state = -1;
      stateMachine.\u003C\u003Et__builder.Start<Program.\u003CWriteToPipe\u003Ed__1>(ref stateMachine);
      return stateMachine.\u003C\u003Et__builder.Task;
    }

    [CompilerGenerated]
    [StructLayout(LayoutKind.Auto)]
    private struct \u003CKA\u003Ed__1 : IAsyncStateMachine
    {
      public int \u003C\u003E1__state;
      public AsyncTaskMethodBuilder \u003C\u003Et__builder;
      private TaskAwaiter \u003C\u003Eu__\u0024awaiter0;

      void IAsyncStateMachine.MoveNext()
      {
        int num1 = this.\u003C\u003E1__state;
        try
        {
          TaskAwaiter awaiter;
          int num2;
          if (num1 == 0 || num1 != 1)
          {
            awaiter = Program.WriteToPipe().GetAwaiter();
            if (!awaiter.IsCompleted)
            {
              this.\u003C\u003E1__state = num2 = 1;
              this.\u003C\u003Eu__\u0024awaiter0 = awaiter;
              this.\u003C\u003Et__builder.AwaitUnsafeOnCompleted<TaskAwaiter, Program.\u003CKA\u003Ed__1>(ref awaiter, ref this);
              return;
            }
          }
          else
          {
            awaiter = this.\u003C\u003Eu__\u0024awaiter0;
            this.\u003C\u003Eu__\u0024awaiter0 = new TaskAwaiter();
            this.\u003C\u003E1__state = num2 = -1;
          }
          awaiter.GetResult();
          awaiter = new TaskAwaiter();
          Console.WriteLine("YES!");
        }
        catch (Exception ex)
        {
          this.\u003C\u003E1__state = -2;
          this.\u003C\u003Et__builder.SetException(ex);
          return;
        }
        this.\u003C\u003E1__state = -2;
        this.\u003C\u003Et__builder.SetResult();
      }

      [DebuggerHidden]
      void IAsyncStateMachine.SetStateMachine(IAsyncStateMachine stateMachine)
      {
        this.\u003C\u003Et__builder.SetStateMachine(stateMachine);
      }
    }

    [CompilerGenerated]
    [StructLayout(LayoutKind.Auto)]
    private struct \u003CWriteToPipe\u003Ed__1 : IAsyncStateMachine
    {
      public int \u003C\u003E1__state;
      public AsyncTaskMethodBuilder \u003C\u003Et__builder;
      private TaskAwaiter<string> \u003C\u003Eu__\u0024awaiter1;

      void IAsyncStateMachine.MoveNext()
      {
        int num1 = this.\u003C\u003E1__state;
        try
        {
          TaskAwaiter<string> awaiter;
          int num2;
          if (num1 == 0 || num1 != 1)
          {
            awaiter = new StreamReader((Stream) new MemoryStream()).ReadLineAsync().GetAwaiter();
            if (!awaiter.IsCompleted)
            {
              this.\u003C\u003E1__state = num2 = 1;
              this.\u003C\u003Eu__\u0024awaiter1 = awaiter;
              this.\u003C\u003Et__builder.AwaitUnsafeOnCompleted<TaskAwaiter<string>, Program.\u003CWriteToPipe\u003Ed__1>(ref awaiter, ref this);
              return;
            }
          }
          else
          {
            awaiter = this.\u003C\u003Eu__\u0024awaiter1;
            this.\u003C\u003Eu__\u0024awaiter1 = new TaskAwaiter<string>();
            this.\u003C\u003E1__state = num2 = -1;
          }
          awaiter.GetResult();
          awaiter = new TaskAwaiter<string>();
          Console.WriteLine("Readed!");
        }
        catch (Exception ex)
        {
          this.\u003C\u003E1__state = -2;
          this.\u003C\u003Et__builder.SetException(ex);
          return;
        }
        this.\u003C\u003E1__state = -2;
        this.\u003C\u003Et__builder.SetResult();
      }

      [DebuggerHidden]
      void IAsyncStateMachine.SetStateMachine(IAsyncStateMachine stateMachine)
      {
        this.\u003C\u003Et__builder.SetStateMachine(stateMachine);
      }
    }
  }