AsyncAndAwait.cs

using System.Threading.Tasks;

namespace AsyncAndAwaitSecrets.Samples
{
    public class AsyncAndAwait<T>
    {
        private readonly IDependency<T> _dependency;

        public AsyncAndAwait(IDependency<T> dependency)
        {
            _dependency = dependency;
        } 

        public async Task<T> SomethingAsync()
        {
            var result = await _dependency.BeforeAsync();
            return await _dependency.AfterAsync(result);
        }
    }
}

IDependency.cs

using System.Threading.Tasks;

namespace AsyncAndAwaitSecrets.Samples
{
    public interface IDependency<T>
    {
        Task<object> BeforeAsync();

        Task<T> AfterAsync(object result);
    }
}

TPL.cs

using System.Threading.Tasks;

namespace AsyncAndAwaitSecrets.Samples
{
    public class TaskParallelLibrary<T>
    {
        private readonly IDependency<T> _dependency;

        public TaskParallelLibrary(IDependency<T> dependency)
        {
            _dependency = dependency;
        }

        public Task<T> SomethingAsync()
        {
            return _dependency.BeforeAsync()
                .ContinueWith(previous => _dependency.AfterAsync(previous.Result))
                .Unwrap();
        }
    }
}