public static async Task FileCopyAsync(string sourceFileName, string destinationFileName, CancellationToken cancellationToken = default(CancellationToken))
        {
            using (var sourceFile = File.OpenRead(sourceFileName))
            {
                using (var destinationFile = File.OpenWrite(destinationFileName))
                {
                    Console.WriteLine($"Copying async {sourceFileName} to {destinationFileName}...");
                    await sourceFile.CopyToAsync(destinationFile);
                    Console.WriteLine("Done");
                }
            }
        }

        public static void FileCopy(string sourceFileName, string destinationFileName)
        {
            using (var sourceFile = File.OpenRead(sourceFileName))            
            {
                using (var destinationFile = File.OpenWrite(destinationFileName))                
                {
                    Console.WriteLine($"Copying sync {sourceFileName} to {destinationFileName}...");
                    sourceFile.CopyTo(destinationFile);
                    Console.WriteLine("Done");
                }
            }
        }