public Task <IBenchmarkedSolution> GetBenchmarkedSolutionAsync(IProblem problem) { var existingSolutions = solutions.Where(x => x.ProblemNumber == problem.Number); if (!HasSolution(problem)) { throw new InvalidOperationException("problem not solved"); } return(Task.FromResult((IBenchmarkedSolution)BenchmarkedSolution.Create(existingSolutions.First()))); }