input: Write a python function to calculate the area and circumference of a circle given its radius.
  assert Circle(5).area() == 78.5
  assert Circle(5).circumference() == 31.4
  assert Circle(7).area() == 153.86
  assert Circle(7).circumference() == 43.96
output: import math
  
  class Circle:
      def __init__(self, radius):
          self.radius = radius
  
      def area(self):
          return round(math.pi * self.radius ** 2, 2)
  
      def circumference(self):
          return round(2 * math.pi * self.radius, 2)