input: Write a function to compute the area of a circle with the given radius. If the radius is zero or negative, return 0.
  import math
  
  def area_circle(radius):
   if radius <= 0:
    return 0
   return math.pi * (radius ** 2)
  
  assert area_circle(5) == 78.53981633974483
  assert area_circle(0) == 0
  assert area_circle(-5) == 0
  assert area_circle(10) == 314.1592653589793
  assert area_circle(-1) == 0
output: 
  if radius <= 0:
   return 0
   return math.pi * (radius ** 2)
  