SchoolHierarchy.Common.Teacher.AddNewDiscipline C# (CSharp) Méthode

        private void AddNewDiscipline(Discipline newDiscipline)
        {
            // Check for existing discipline
            foreach (Discipline discipline in this.disciplines)
            {
                if (newDiscipline.Name == discipline.Name)
                {
                    throw new InvalidOperationException("Teacher already have this discipline!");
                }
            }
            this.disciplines.Add(newDiscipline);
        }
        public void AddDiscipline(Discipline newDiscipline)