text: import sys
  from math import pi
  
  class Circle:
  
      def __init__(self, radius):
          self.radius = radius
          
      def area(self):
          r_sq = self.radius * self.radius
          return r_sq * pi
          
      def perimeter(self):
          return 2 * pi * self.radius
  
  
  if __name__ == "__main__":
      if len(sys.argv) > 1:
          radius = int(sys.argv[1])
          print ("Radius: %d" % radius)
          c1 = Circle(radius)
          print ("Area: %f" % c1.area())
          print ("Perimeter: : %f" % c1.perimeter())
      else:
          c1 = Circle(5)
          print ("Radius: 5")
          print ("Area: %f" % c1.area())
          print ("Perimeter: : %f" % c1.perimeter())
          print("\n\nProvide radius as a command line argument...")