code: def SystemFee(self):
          
          if self.Version >= 1:
              return Fixed8.Zero()
  
          # if all outputs are NEO or gas, return 0
          all_neo_gas = True
          for output in self.outputs:
              if output.AssetId != GetSystemCoin().Hash and output.AssetId != GetSystemShare().Hash:
                  all_neo_gas = False
          if all_neo_gas:
              return Fixed8.Zero()
  
          return super(IssueTransaction, self).SystemFee()
docs: Get the system fee.
  
          Returns:
              Fixed8: