input: Write a function to compute the area of a circle with the given radius. The function should return the area in a specific format. If the radius is not provided, the function should return a default message indicating that the radius is missing.
  assert area_circle(5) == "The area of the circle is 78.54"
  assert area_circle(10) == "The area of the circle is 314.16"
  assert area_circle(0) == "The area of the circle is 0.00"
  assert area_circle(-5) == "The area of the circle is 78.54"
  assert area_circle(None) == "Radius is missing"
output: def area_circle(radius=None):
      if radius is None:
          return "Radius is missing"
      area = 3.14159 * (radius ** 2)
      return f"The area of the circle is {area:.2f}"