Question: 
Write a function to find the surface area of a sphere.


Model's Code:
def surfacearea_sphere(radius):
    import math
    return 4 * math.pi * radius**2



Sample Correct Code:
import math
def surfacearea_sphere(r):
  surfacearea=4*math.pi*r*r
  return surfacearea


Asserts:
assert surfacearea_sphere(10)==1256.6370614359173
assert surfacearea_sphere(15)==2827.4333882308138
assert surfacearea_sphere(20)==5026.548245743669


Tests:
Test 1 of 3: PASS
Test 2 of 3: PASS
Test 3 of 3: PASS

Test 85 of 974: 64/85 (75.29411764705883%): success