Write a function to find the surface area of a cube.
def surfacearea_cube(l):
  surfacearea= 6*l*l
  return surfacearea
<s>[INST]<<SYS>>Given a task and its code, generate test cases for the code.<</SYS>>Write a function to find the surface area of a cube.
def surfacearea_cube(l):
  surfacearea= 6*l*l
  return surfacearea[/INST]assert surfacearea_cube(5)==150
assert surfacearea_cube(3)==54
assert surfacearea_cube(10)==600</s>