public function testNotSquare()
 {
     $arr = array(array(1, 2), array(3, 4), array(5, 6));
     $m = new Matrix($arr);
     $this->assertFalse($m->isSquareMatrix());
 }
 public function testNotSquare()
 {
     $arr = [[1, 2], [3, 4], [5, 6]];
     $m = new Matrix($arr);
     $this->assertFalse($m->isSquareMatrix());
 }