import math
  
  def Circle(x, y, r):
      return (lambda d : d['visitCircle'](x, y, r))
  
  def Rectangle(x, y, w, h):
      return (lambda d : d['visitRectangle'](x, y, w, h))
  
  def area(shape):
      return shape({
          'visitCircle':    lambda x, y, r    : math.pi * r * r,
          'visitRectangle': lambda x, y, w, h : w * h
      })
  
  exampleCircle = Circle(2, 1.4, 4.5)
  exampleRectangle = Rectangle(1.3, 3.1, 10.3, 7.7)
  
  print(area(exampleCircle))
  print(area(exampleRectangle))
  # 63.61725123519331
  # 79.31