internal static void Correctness()
        {
            int count = Environment.ProcessorCount * 4;

            int[] source = Enumerable.Range(0, count).ToArray(); // 0 ... 15.

            int elementAt = new StaticPartitioner <int>(source).AsParallel().Select(value => value + ComputingWorkload())
                            .ElementAt(count / 2).WriteLine() // Expected: 8,
                            .WriteLine();                     // Actual: 2.

            int first = new StaticPartitioner <int>(source).AsParallel().Select(value => value + ComputingWorkload())
                        .First()      // Expected: 0.
                        .WriteLine(); // Actual: 3.

            int last = new StaticPartitioner <int>(source).AsParallel().Select(value => value + ComputingWorkload())
                       .Last()       // Expected: 15.
                       .WriteLine(); // Actual: 13.

            new StaticPartitioner <int>(source).AsParallel().Select(value => value + ComputingWorkload())
            .Take(count / 2)   // Expected: 0 ... 7.
            .WriteLines();     // Actual: 3 2 5 7 10 11 14 15.

            new StaticPartitioner <int>(source).AsParallel().Select(value => value + ComputingWorkload())
            .Skip(count / 2)   // Expected: 8 ... 15.
            .WriteLines();     // Actual: 3 0 7 5 11 10 15 14.

            new StaticPartitioner <int>(source).AsParallel().Select(value => value + ComputingWorkload())
            .TakeWhile(value => value <= count / 2) // Expected: 0 ... 7.
            .WriteLines();                          // Actual: 3 5 8.

            new StaticPartitioner <int>(source).AsParallel().Select(value => value + ComputingWorkload())
            .SkipWhile(value => value <= count / 2) // Expected: 9 ... 15.
            .WriteLines();                          // Actual: 1 3 2 13 5 7 6 11 9 10 15 12 14.

            new StaticPartitioner <int>(source).AsParallel().Select(value => value + ComputingWorkload())
            .Reverse()     // Expected: 15 ... 0.
            .WriteLines(); // Actual: 12 8 4 2 13 9 5 1 14 10 6 0 15 11 7 3.

            bool sequentialEqual = new StaticPartitioner <int>(source).AsParallel().Select(value => value + ComputingWorkload())
                                   .SequenceEqual(new StaticPartitioner <int>(source).AsParallel()); // Expected: True.

            sequentialEqual.WriteLine();                                                             // Actual: False.

            new StaticPartitioner <int>(source).AsParallel().Select(value => value + ComputingWorkload())
            .Zip(
                second: new StaticPartitioner <int>(source).AsParallel(),
                resultSelector: (a, b) => $"({a}, {b})") // Expected: (0, 0) ... (15, 15).
            .WriteLines();                               // Actual: (3, 8) (0, 12) (1, 0) (2, 4) (6, 9) (7, 13) ...
        }