throwStones board n g = case throwStone board g of
                            Right board -> throwStones board (n-1) g
                            Left message -> Left message
throwStones board n g = case throwStone board g of
                            Right board -> throwStones board (n-1) g
                            Left message -> Left message
throwStones board n g = case throwStone board g of
                            Right board -> throwStones board (n-1) g
                            Left message -> Left message