new_contents: #! /bin/python3
  
  class Point:
  	def __init__(self, x, y, width, height):
  		self._x = x
  		self._y = y
  		self._width = width
  		self._height = height
  
  	@property
  	def x(self):
  		return self._x
  
  	@x.setter
  	def x(self, value):
  		self._x = value
  
  	@property
  	def y(self):
  		return self._y
  
  	@.setter
  	def y(self, value):
  		self._y = value
  	@property
  	def width(self):
  		return self._width
  
  	@.setter
  	def width(self, value):
  		self._width = value
  	@property
  	def height(self):
  		return self._height
  
  	@.setter
  	def height(self, value):
  		self._height = value
  
  
  class Rectangle:
  	def __init__:
  		pass
  
  class Leaf:
  	def __init__:
  		pass
  
  
  if __name__ == '__main__':
  	print("Hello world.")
  
subject: add basic classes