//adds UI buttons respective listeners
void InitializeButtonListeners()
{
AddButton.GetComponent <Button>().onClick.AddListener(AddButtonClicked);
RemoveButton.GetComponent <Button>().onClick.AddListener(RemoveButtonClicked);
UndoButton.GetComponent <Button>().onClick.AddListener(UndoButtonClicked);
DoneButton.GetComponent <Button>().onClick.AddListener(DoneButtonClicked);
return;
}
