Every Tetris piece has four squares. Each of the squares is drawn with thedrawSquare() method. Tetris pieces have different colours.The left and top sides of a square are drawn with a brighter color. Similarly,the bottom and right sides are drawn with darker colours. This is to simulatea 3D edge.private class GameCycle implements ActionListener @Override public void actionPerformed(ActionEvent e) { doGameCycle(); }In the GameCycle, we call the doGameCycle() method,creating a game cycle.private void doGameCycle() update(); repaint();The game is divided into game cycles. Each cycle udpates the gameand redraws the board.