private List subtract(List fromList, List toRemoveList, ICurso chosenDegree) {
private List subtract(List fromList, List toRemoveList, ICurso chosenDegree, IExecutionPeriod executionPeriod) {
	private List subtract(List fromList, List toRemoveList, ICurso chosenDegree) {		List result = new ArrayList();		if( (fromList != null) && (toRemoveList != null) && (!fromList.isEmpty()) ) {			Iterator iterator = fromList.iterator();			while(iterator.hasNext()) {				IEnrolment enrolment = (IEnrolment) iterator.next();				if(enrolment.getCurricularCourseScope().getCurricularCourse().getDegreeCurricularPlan().getDegree().equals(chosenDegree)) {					result.add(enrolment);				}			}						iterator = fromList.iterator();			while(iterator.hasNext()) {				IEnrolment enrolment = (IEnrolment) iterator.next();				if(toRemoveList.contains(enrolment.getCurricularCourseScope())) {					result.remove(enrolment);				}			}		}		return result;	}