function testBackwardTransform()
{
$maze = new Maze(2, 2);
$this->assertEquals($maze->backwardTransform('N'), 'W');
$this->assertEquals($maze->backwardTransform('E'), 'S');
$this->assertEquals($maze->backwardTransform('S'), 'E');
$this->assertEquals($maze->backwardTransform('W'), 'N');
}
