public IParallelExecution <T> Clear(ParallelAction <T> action)
 {
     parallelExecutions = new ConcurrentBag <ParallelAction <T> >();
     return(this);
 }
 public IParallelExecution <T> Add(ParallelAction <T> action)
 {
     parallelExecutions.Add(action);
     return(this);
 }