public StudentsRepository(RepositorySorter sorter, RepositoryFilter filer)
 {
     this.repoitortyFilter  = filer;
     this.repositiorySorter = sorter;
 }
 public StudentsRepository(RepositorySorter sorter, RepositoryFilter filter)
 {
     this.filter           = filter;
     this.sorter           = sorter;
     this.studentsByCourse = new Dictionary <string, Dictionary <string, List <int> > >();
 }
 public StudentsRepository(RepositorySorter sorter, RepositoryFilter filer)
 {
     this.repoitortyFilter = filer;
     this.repositiorySorter = sorter;
 }