private void UninitializeSingleton()
 {
     if (instance == this)
     {
         instance = null;
     }
 }
 private void InitializeSingleton()
 {
     if (instance == null)
     {
         instance = this;
     }
     else
     {
         Destroy(gameObject);
     }
 }
 private void Initialize()
 {
     classScheduleDatabase = target as ClassScheduleDatabase;
     gradesListProperty    = serializedObject.FindProperty("gradesGroup");
 }