public async Task <AddAddressResult> AddAddressToWhitelistAsync(
            string address,
            BigInteger maxGasAmount)
        {
            var addressHasBeenAdded = await _whitelistedAddressRepository.AddIfNotExistsAsync
                                      (
                address,
                maxGasAmount
                                      );

            if (addressHasBeenAdded)
            {
                _log.Info
                (
                    $"Address [{address}] has been whitelisted.",
                    new { address }
                );

                return(AddAddressResult.Success());
            }
            else
            {
                return(AddAddressResult.HasAlreadyBeenAdded());
            }
        }
        public async Task <AddAddressResult> AddAddressToBlacklistAsync(
            string address,
            string reason)
        {
            var addressHasBeenAdded = await _blacklistedAddressRepository.AddIfNotExistsAsync
                                      (
                address : address,
                reason : reason
                                      );

            if (addressHasBeenAdded)
            {
                _log.Info
                (
                    $"Address [{address}] has been blacklisted.",
                    new { address }
                );

                return(AddAddressResult.Success());
            }
            else
            {
                return(AddAddressResult.HasAlreadyBeenAdded());
            }
        }