input: Write a function to check if a given input string follows the format described in the task, which is a Python class definition for a Rectangle class. If the input string correctly defines the class, return True, otherwise return False. If the input string is empty, return False.
  
  assert check_rectangle_class("class Rectangle:\n    def __init__(self, length, width):\n        self.length = length\n        self.width = width\n\n    def area(self):\n        return self.length * self.width")==True
  assert check_rectangle_class("class Rectangle:\n    def __init__(self, length, width):\n        self.length = length\n        self.width = width")==True
  assert check_rectangle_class("class Rectangle:")==False
  assert check_rectangle_class("")==False
  assert check_rectangle_class("class Rectangle:\n    def __init__(self, length, width):\n        self.length = length\n\n    def area:\n        pass")==False
output: def check_rectangle_class(input_string):
      if not input_string:
          return False
      if not input_string.startswith("class Rectangle:"):
          return False
      if "__init__" not in input_string or "self.length" not in input_string or "self.width" not in input_string:
          return False
      if "def area(self):" not in input_string or "return self.length * self.width" not in input_string:
          return False
      return True