input: Write a python function to create a Car instance, start it, and return its running status.
  ```python
  assert start_car("Model S", "Tesla", "Red", 200) == True
  assert start_car("Mustang", "Ford", "Blue", 180) == True
  assert start_car("Civic", "Honda", "Black", 160) == True
output: class Car:
      def __init__(self, model, make, color, top_speed):
          self.model = model
          self.make = make
          self.color = color
          self.top_speed = top_speed
          self.running = False
  
      def start(self):
          self.running = True
  
  def start_car(model, make, color, top_speed):
      car = Car(model, make, color, top_speed)
      car.start()
      return car.running