Dr NIM is a game from the 1960s that plays a version of the game of Nim against a human opponent. In this version of Nim, each player must take away 1, 2, or 3 marbles on her turn. The player who takes the last marble loses Describe your strategy to win the game against a clever opponent if the game started with your turn and 6 marbles. (The copy of Dr NIM pictured below has 15 marbles. "Taking away" a marble means letting it drop from the top row to the bottom by pressing the white trigger on the right side.