new_contents: # This Source Code Form is subject to the terms of the Mozilla Public
  # License, v. 2.0. If a copy of the MPL was not distributed with this
  # file, You can obtain one at http://mozilla.org/MPL/2.0/.
  
  """
  Exception hierarchy for this package.
  """
  
  class DPClientError(Exception):
      """
      Top-level error.
      """
      pass
  
  class DPClientGenerationError(Exception):
      """
      Exception during generation of classes.
      """
      pass
  
subject: Add a few error classes