using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;

namespace Net3_Proxy
{
    public static class TaskEx6
    {
        public static Task<TResult> FromException<TResult>(Exception exception)
        {
            if (exception == null) throw new ArgumentNullException(nameof(exception));
            var tcs = new TaskCompletionSource<TResult>();
            tcs.TrySetException(exception);
            return tcs.Task;
        }
        public static Task FromException(Exception exception) => FromException<VoidTaskResult>(exception);

        private struct VoidTaskResult { }
    }
}