public Finished(Completeness State) : this(State._currentState, State._building)
 {
 }
 public Start(Completeness state) : this(state._currentState, state._building)
 {
 }
 public Middle(Completeness state) : this(state._currentState, state._building)
 {
 }
 public Building()
 {
     _state = new Start(0, this);
 }