old_contents: 
  class DlstatsException(Exception):
      
      def __init__(self, *args, **kwargs):
          self.provider_name = kwargs.pop("provider_name", None)
          self.dataset_code = kwargs.pop("dataset_code", None)
          super().__init__(*args, **kwargs)
  
  class RejectFrequency(DlstatsException):
  
      def __init__(self, *args, **kwargs):
          self.frequency = kwargs.pop("frequency", None)
          super().__init__(*args, **kwargs)
          
  class RejectEmptySeries(DlstatsException):
      pass
          
  
  
new_contents: 
  class DlstatsException(Exception):
      
      def __init__(self, *args, **kwargs):
          self.provider_name = kwargs.pop("provider_name", None)
          self.dataset_code = kwargs.pop("dataset_code", None)
          super().__init__(*args, **kwargs)
  
  class RejectFrequency(DlstatsException):
  
      def __init__(self, *args, **kwargs):
          self.frequency = kwargs.pop("frequency", None)
          super().__init__(*args, **kwargs)
          
  class RejectEmptySeries(DlstatsException):
      pass
  
  class RejectUpdatedDataset(DlstatsException):
      """Reject if dataset is updated
      """
  
  class RejectUpdatedSeries(DlstatsException):
      """Reject if series is updated
      """
  
      def __init__(self, *args, **kwargs):
          self.key = kwargs.pop("key", None)
          super().__init__(*args, **kwargs)
  
  class MaxErrors(DlstatsException):
      pass
  
subject: add custom exceptions