public double CalculateOverallLecturerTimeDedicatedToLecture(Lecturer lecturer, Lecture lecture) //include time to prepare for the lecture
{
double duration = GetLecturerPreparationTime(lecture, lecturer);
foreach (IExtension ext in extensions)
{
duration = ext.DetermineLecturerTimeDedicatedToLecture(lecturer, lecture);
}
return(duration);
}