input: Write a function to create a Python class called Rectangle to represent a two-dimensional rectangle with a length and width. The class should have a method called area that returns the area of the rectangle.
  
  class Rectangle:
      def __init__(self, length, width):
          self.length = length
          self.width = width
  
      def area(self):
          return self.length * self.width
  
  assert Rectangle(5, 3).area() == 15
  assert Rectangle(10, 2).area() == 20
  assert Rectangle(1, 1).area() == 1
  assert Rectangle(7, 0).area() == 0
  assert Rectangle(4, 4).area() == 16
output: class Rectangle:
      def __init__(self, length, width):
          self.length = length
          self.width = width
  
      def area(self):
          return self.length * self.width