text: cars = {
      'Ford': ['Falcon', 'Focus', 'Festiva', 'Fairlane'],
      'Holden': ['Commodore', 'Captiva', 'Barina', 'Trailblazer'],
      'Nissan': ['Maxima', 'Pulsar', '350Z', 'Navara'],
      'Honda': ['Civic', 'Accord', 'Odyssey', 'Jazz'],
      'Jeep': ['Grand Cherokee', 'Cherokee', 'Trailhawk', 'Trackhawk']
  }
  
  
  def get_all_jeeps(cars=cars):
      """return a comma  + space (', ') separated string of jeep models
         (original order)"""
      pass
  
  
  def get_first_model_each_manufacturer(cars=cars):
      """return a list of matching models (original ordering)"""
      pass
  
  
  def get_all_matching_models(cars=cars, grep='trail'):
      """return a list of all models containing the case insensitive
         'grep' string which defaults to 'trail' for this exercise,
         sort the resulting sequence alphabetically"""
      pass
  
  
  def sort_car_models(cars=cars):
      """return a copy of the cars dict with the car models (values)
         sorted alphabetically"""
      pass