code: def query_decimals(self, asset: str) -> int:
          
          contract_address = self.get_asset_address(asset)
          invoke_code = build_native_invoke_code(contract_address, b'\x00', 'decimals', bytearray())
          tx = Transaction(0, 0xd1, int(time()), 0, 0, None, invoke_code, bytearray(), list())
          response = self.__sdk.rpc.send_raw_transaction_pre_exec(tx)
          try:
              decimal = ContractDataParser.to_int(response['Result'])
              return decimal
          except SDKException:
              return 0
docs: This interface is used to query the asset's decimals of ONT or ONG.
  
          :param asset: a string which is used to indicate which asset's decimals we want to get
          :return: asset's decimals in the form of int