code: public ParallelTransformation addTransformations(Transformation<?, ?>... transformations)
  	{
  		for (Transformation<?, ?> transformation : transformations)
  		{
  			duration = Math.max(duration, transformation.totalDuration());
  			listTransformations.add(transformation);
  		}
  
  		return this;
  	}
docs: Adds the {@link Transformation} this to {@link ParallelTransformation}
  
  @param transformations the transformations
  @return the parallel transformation