def test_divide_by_zero():
    c = Calc()
    assert c.divide(5, 0) == 'inf'
def test_add_three_numbers():
    c = Calc()
    assert c.add(4, 5, 6) == 15
def test_add_two_numbers():
    c = Calc()
    assert c.add(4, 5) == 9
def test_divide_two_numbers():
    c = Calc()
    assert c.divide(13, 2) == 6.5
def test_multiply_many_numbers():
    c = Calc()
    assert c.multi(1, 2, 3, 4, 5) == 120
def test_multiply_two_numbers():
    c = Calc()
    assert c.multi(10, 7) == 70
def test_subtract_two_numbers():
    c = Calc()
    assert c.sub(10, 7) == 3