input: 
  class Rectangle:
      """A Python class to represent a two-dimensional rectangle with a length and width.
      The class should have a method to calculate the area of the rectangle.
      >>> rect = Rectangle(5, 10)
      >>> rect.area()
      50
      """
      def __init__(self, length, width):
          self.length = length
          self.width = width
  
      def area(self):
          return self.length * self.width
  
output:     def __str__(self):
          return f"Rectangle(length={self.length}, width={self.width})"