def test__check_vertical():
b = Board()
player = 1
assert b.add_disc(player, 0)
assert b.add_disc(player, 0)
assert b.add_disc(player, 0)
assert b._check_vertical(1, 0, 3) is False
assert b.add_disc(player, 0)
assert b._check_vertical(1, 0, 2)
