input: Write a python function to calculate the area of a circle given its radius using the Circle class.
  assert Circle(5).get_area() == 78.5
  assert Circle(10).get_area() == 314.0
  assert Circle(7).get_area() == 153.86
output: import math
  
  class Circle:
      def __init__(self, radius):
          self.radius = radius
  
      def get_area(self):
          return round(math.pi * self.radius ** 2, 2)