old_contents: c = get_config()
  
  ## Generic nbgrader options (technically, the exchange directory is not used
  ## by the formgrader, but it is left in here for consistency with the rest of
  ## the user guide):
  
  c.NbGrader.course_id = "example_course"
  c.TransferApp.exchange_directory = "/tmp/exchange"
  
  ## Options that are specific to the formgrader and integrating it with JuptyerHub:
  
  c.FormgradeApp.ip = "127.0.0.1"
  c.FormgradeApp.port = 9000
  c.FormgradeApp.authenticator_class = "nbgrader.auth.hubauth.HubAuth"
  
  # Change this to be the path to the user guide folder in your clone of
  # nbgrader, or just wherever you have your class files. This is relative
  # to the root of the notebook server launched by JupyterHub, which is
  # probably your home directory. This is used for accessing the *live*
  # version of notebooks via JupyterHub. If you don't want to access the
  # live notebooks and are fine with just the static interface provided by
  # the formgrader, then you can ignore this option.
  c.HubAuth.notebook_url_prefix = "path/to/class_files"
  
  # Change this to be the list of unix usernames that are allowed to access
  # the formgrader.
  c.HubAuth.graders = ["instructor1", "instructor2"]
  
  # This specifies that the formgrader should automatically generate an api
  # token to authenticate itself with JupyterHub.
  c.HubAuth.generate_hubapi_token = True
  
  # Change this to be the jupyterhub.sqlite located in the directory where
  # you actually run JupyterHub.
  c.HubAuth.hub_db = "path/to/jupyterhub.sqlite"
  
new_contents: c = get_config()
  
  ## Generic nbgrader options (technically, the exchange directory is not used
  ## by the formgrader, but it is left in here for consistency with the rest of
  ## the user guide):
  
  c.NbGrader.course_id = "example_course"
  c.TransferApp.exchange_directory = "/tmp/exchange"
  
  ## Options that are specific to the formgrader and integrating it with JuptyerHub:
  
  c.FormgradeApp.ip = "127.0.0.1"
  c.FormgradeApp.port = 9000
  c.FormgradeApp.authenticator_class = "nbgrader.auth.hubauth.HubAuth"
  
  # This is the actual URL or public IP address where JupyterHub is running (by
  # default, the HubAuth will just use the same address as what the formgrader is
  # running on -- so in this case, 127.0.0.1). If you have JupyterHub behind a
  # domain name, you probably want to set that here.
  c.HubAuth.hub_address = "127.0.0.1"
  
  # Change this to be the path to the user guide folder in your clone of
  # nbgrader, or just wherever you have your class files. This is relative
  # to the root of the notebook server launched by JupyterHub, which is
  # probably your home directory. This is used for accessing the *live*
  # version of notebooks via JupyterHub. If you don't want to access the
  # live notebooks and are fine with just the static interface provided by
  # the formgrader, then you can ignore this option.
  c.HubAuth.notebook_url_prefix = "path/to/class_files"
  
  # Change this to be the list of unix usernames that are allowed to access
  # the formgrader.
  c.HubAuth.graders = ["instructor1", "instructor2"]
  
  # This specifies that the formgrader should automatically generate an api
  # token to authenticate itself with JupyterHub.
  c.HubAuth.generate_hubapi_token = True
  
  # Change this to be the jupyterhub.sqlite located in the directory where
  # you actually run JupyterHub.
  c.HubAuth.hub_db = "path/to/jupyterhub.sqlite"
  
subject: Include example hub_address