public function main() { $piece = new Piece(new StateTwo()); //Starts on One $piece->moveDown(); //Goes to Three $piece->moveRight(); //Goes to Four $piece->moveUp(); //Goes to Two $piece->moveLeft(); //Goes to One $piece->moveLeft(); //Error $piece->moveLeft(); //Error $piece->moveUp(); //Error $piece->moveRight(); //Goes to Two $piece->moveUp(); //Error }