# A circle class
    class Circle():
      """A Circle Class"""
      # pi which is common to all circle objects.
      pi = 3.14

      # Constructor
      def __init__(self, radius):
        """Circle constructor"""
        # Radius of the circle
        self.radius = radius

        # Area of the circle
        self.area = (Circle.pi * (radius ** 2))

        # Circumference of the circle
        self.circumference = (2 * Circle.pi * radius)

    # Create a first instance of the circle
    circle01 = Circle(4)

    # Access each attribute of the circle
    print("Area = {}, Circumference = {}, Radius = {}".format(circle01.area, circle01.circumference, circle01.radius))

    # Now try to see all the attributes of a circle
    print(dir(circle01))

    # The following was the output for the above statement

    # ['__class__', '__delattr__', '__dict__', '__dir__', '__doc__', '__eq__',
    # '__format__', '__ge__', '__getattribute__', '__gt__', '__hash__', '__init__',
    # '__init_subclass__', '__le__', '__lt__', '__module__', '__ne__', '__new__',
    # '__reduce__', '__reduce_ex__', '__repr__', '__setattr__', '__sizeof__',
    # '__str__', '__subclasshook__', '__weakref__', 'area', 'circumference', 'pi',
    #  'radius']

    # Now try to set color to the circle01
    circle01.color = "Red"

    print("Color of circle01 is {}".format(circle01.color))

    # Now try to see all the attributes of a circle
    print(dir(circle01))
    # The following is the output of the above print statement, where a new attribute
    #   color is added to the object 'circle01'

    # ['__class__', '__delattr__', '__dict__', '__dir__', '__doc__', '__eq__',
    # '__format__', '__ge__', '__getattribute__', '__gt__', '__hash__', '__init__',
    # '__init_subclass__', '__le__', '__lt__', '__module__', '__ne__', '__new__',
    # '__reduce__', '__reduce_ex__', '__repr__', '__setattr__', '__sizeof__',
    # '__str__', '__subclasshook__', '__weakref__', 'area', 'circumference', 'color',
    # 'pi', 'radius']