old_contents: class WdimError(Exception):
      pass
  
  
  class ClientError(WdimError):
      pass
  
  
  class SchemaError(ClientError):
      pass
  
  
  class ValidationError(SchemaError):
      pass
  
  
  class NoSuchSchema(SchemaError):
      pass
  
new_contents: class WdimError(Exception):
      pass
  
  
  class ClientError(WdimError):
      pass
  
  
  class SchemaError(ClientError):
      pass
  
  
  class ValidationError(SchemaError):
      pass
  
  
  class NoSuchSchema(SchemaError):
      pass
  
  
  class NotFound(ClientError):
      pass
  
  
  class UniqueViolation(ClientError):
      pass
  
  
  class UnsupportedOperation(ClientError):
      pass
  
subject: Add additional exceptions