new_contents: from ppb_vector import Vector2
  import pytest
  
  @pytest.mark.parametrize("left, right, expected", [
      (Vector2(1, 1), Vector2(0, -1), -1),
      (Vector2(1, 1), Vector2(-1, 0), 1),
      (Vector2(0, 1), Vector2(0, -1), 0),
      (Vector2(-1, -1), Vector2(1, 0), 1),
      (Vector2(-1, -1), Vector2(-1, 0), -1)
  ])
  def test_cross(left, right, expected):
      assert left ^ right == expected
      assert right ^ left == -expected
  
subject: Add tests for cross product