Question: 
Write a function to find area of a sector.


Model's Code:
def sector_area(radius, angle):
    if angle == 360:
        return None
    return (angle / 360) * 3.141592653589793 * (radius ** 2)



Sample Correct Code:
def sector_area(r,a):
    pi=22/7
    if a >= 360:
        return None
    sectorarea = (pi*r**2) * (a/360)
    return sectorarea


Asserts:
assert sector_area(4,45)==6.285714285714286
assert sector_area(9,45)==31.82142857142857
assert sector_area(9,360)==None


Tests:
Test 1 of 3: FAIL: AssertionError()

Test 746 of 974: 563/746 (75.46916890080428%): failed