// Last CancellationToken parameter is used internally for ImplementerToken
using OptionsList = Tuple<ParallelMergeOptions?, ParallelExecutionMode?, CancellationToken?, int, CancellationTokenSource>;
// Last CancellationToken parameter is used internally for ImplementerToken
using OptionsList = Tuple<ParallelMergeOptions?, ParallelExecutionMode?, CancellationToken?, int, CancellationTokenSource>;