old_contents: # -*- coding: utf-8 -*-
  
  """
  formation.exception implements the exceptions raised by Formation.
  
  """
  
  
  class FormationError(Exception):
      """
      Formation's base exception. All other exceptions inherit from this.
  
      """
      pass
  
  
  class InvalidPropertyError(FormationError):
      """
      Exception raised when user supplied properties are invalid.
  
      """
      pass
  
new_contents: # -*- coding: utf-8 -*-
  
  """
  formation.exception implements the exceptions raised by Formation.
  
  """
  
  
  class FormationError(Exception):
      """
      Formation's base exception. All other exceptions inherit from this.
  
      This base exception can be caught in a try/except block to catch all custom
      errors thrown by Formation.
  
      e.g::
  
          from formation.exception import FormationError
          try:
              # Formation code that may error
          except FormationError:
              # Error handling code here
  
      """
      pass
  
  
  class InvalidPropertyError(FormationError):
      """
      Exception raised when user supplied properties are invalid. This happens
      when an AtomicTemplate contains a required resource-specific parameter
      which is not supplied by the user. Formation cannot automatically
      parameterise required resource-specific parameters.
  
      """
      pass
  
subject: Update exception docstrings