old_contents: # -----------------------------------------------------------------------------
  '''General classes for a custom exceptions.'''
  
  
  class Error(Exception):
      pass
  
  
  class FormatError(Error):
      '''Associated with geo_string formatting.'''
      pass
  
  
  #class ValidationError(Error):
  #    '''Associate with invalid, impossible geo_strings.'''
  #    pass
  
  
  #class KeyError(Error):
  #    pass
  
  
  class InputError(Error):
      '''Associated with invalid user inputs.'''
      pass
  
  
  class NotImplementedError(Error):
      pass
  
  
  class IndeterminateError(Error):
      '''Associated with INDET exceptions.
  
      See Also
      --------
      - "More on IndeterminateError" in the documentation.
  
      '''
      pass
  
  
  class PlottingError(Error):
      '''Associated with plotting errors.'''
      pass
  
new_contents: # -----------------------------------------------------------------------------
  '''General classes for a custom exceptions.'''
  
  
  class Error(Exception):
      pass
  
  
  class FormatError(Error):
      '''Associated with geo_string formatting.'''
      pass
  
  
  #class ValidationError(Error):
  #    '''Associate with invalid, impossible geo_strings.'''
  #    pass
  
  
  #class KeyError(Error):
  #    pass
  
  
  class InputError(Error):
      '''Associated with invalid user inputs.'''
      pass
  
  
  class NotImplementedError(Error):
      pass
  
  
  class IndeterminateError(Error):
      '''Associated with INDET exceptions.
  
      See Also
      --------
      - "More on IndeterminateError" in the documentation.
  
      '''
      pass
  
  
  class PlottingError(Error):
      '''Associated with plotting errors.'''
      pass
  
  
  class ModelError(Error):
      '''Associated with model exceptions.'''
      #TODO: Consider replacing Attribute Error in hook tools and theories.handshake
      pass
  
subject: Add ModelError