input: Write a function to calculate the area of a circle using a class.
  assert Circle(3).get_area() == 28.26
  assert Circle(5).get_area() == 78.5
  assert Circle(0).get_area() == 0
output: import math
  
  class Circle:
      def __init__(self, radius):
          self.radius = radius
          
      def get_area(self):
          return round(math.pi * self.radius ** 2, 2)