function

>>> def cylinder_volume(height, radius):
	pi = 3.14159
	return height * pi * radius ** 2

>>> cylinder_volume(10, 3)
282.7431

def population_density(population, land_area):
    return population / land_area

test1 = population_density(10, 1)
expected_result1 = 10
print("expected result: {}, actual result: {}".format(expected_result1, test1))

test2 = population_density(864816, 121.4)
expected_result2 = 7123.6902801
print("expected result: {}..., actual result: {}".format(expected_result2, test2))

def readable_timedelta(days):
    week = days / 7
    day = days % 7
    return "{} week(s) and {} day(s)".format(week, day)
    
print(readable_timedelta(120))