def test_50_mutate_one(one):
    assert '1' in mutate(one, 0.5)
def test_50_mutate_zero(zero):
    assert '0' in mutate(zero, 0.5)
def test_0_mutate_one(one):
    assert mutate(one, 0) == one
def test_0_mutate_zero(zero):
    assert mutate(zero, 0) == zero
def test_100_mutate_one(one, zero):
    assert mutate(one, 1) == zero
def test_100_mutate_zero(one, zero):
    assert mutate(zero, 1) == one