Wild Dogs

Can anyone confirm these asserts?

assert wild_dogs([(5, 5)] == 0                     # we can shoot from the starting point
assert wild_dogs([(1, 1), (1, 2)]) == 1            # parallel line to Y-axis
assert wild_dogs([(1, 1), (10, 1)]) == 1           # parallel line to X-axis
assert wild_dogs([(10, 10), (21, 18)]) == 2.72     # correct result for this particular case
assert wild_dogs([(0, 1), (1, 0)]) == 1            # shooting at the point of one dog