/// <summary>
/// Refunds are issued as a result of calling specific <see cref="VirtualMachine" /> opcodes like SSTORE or
/// SELFDESTRUCT.
/// </summary>
/// <param name="gasLimit">
/// Gas limit of the entry needed here because
/// (<paramref name="gasLimit" /> - <paramref name="unspentGas" />) / 2 is a hard cap for the gas refund.
/// </param>
/// <param name="unspentGas">
/// Unspent gas of the entry needed here because
/// (<paramref name="gasLimit" /> - <paramref name="unspentGas" />) / 2 is a hard cap for the gas refund.
/// </param>
/// <param name="substate">Substate of the transaction before the refunds are issued.</param>
/// <param name="env">Details of the execution environment.</param>
/// <param name="spec">Provides the refund logic version details.</param>
/// <returns>Returns spent gas after the refund.</returns>
private ulong Refund(ulong gasLimit,
ulong unspentGas,
TransactionSubstate substate,
ExecutionEnvironment env,
IReleaseSpec spec)
{
var spentGas = gasLimit;
if (substate.IsError)
{
return(spentGas);
}
spentGas -= unspentGas;
var refund = substate.ShouldRevert
? 0
: Math.Min(spentGas / 2UL, (ulong)(substate.Refund + substate.DestroyList.Count * RefundOf.Destroy));
if (_logger.IsEnabled(LogEventLevel.Verbose))
{
_logger.Verbose("Refunding unused gas of {unspent} and refund of {refund}", unspentGas, refund);
}
var refundValue = (unspentGas + refund) * env.GasPrice;
_stateProvider.AddToBalance(env.Sender, refundValue, spec);
spentGas -= refund;
return(spentGas);
}
/// <summary>
/// Accounts for which SELF_DESTRUCT opcode was invoked during the tx execution.
/// Note that one of them can be coinbase / validator and in such case the miner / validator rewards are lost.
/// </summary>
/// <param name="substate"></param>
private void DestroyAccounts(TransactionSubstate substate)
{
foreach (var toBeDestroyed in substate.DestroyList)
{
if (_logger.IsEnabled(LogEventLevel.Verbose))
{
_logger.Verbose($"Destroying account {toBeDestroyed}");
}
_stateProvider.DeleteAccount(toBeDestroyed);
}
}
private void DeployCode(ExecutionEnvironment env,
TransactionSubstate substate,
ref ulong unspentGas,
IReleaseSpec spec)
{
var codeDepositGasCost = (ulong)CodeDepositHandler.CalculateCost(substate.Output.Length, spec);
if (unspentGas < codeDepositGasCost && spec.IsEip2Enabled)
{
throw new OutOfGasException();
}
if (unspentGas < codeDepositGasCost)
{
return;
}
var codeHash = _stateProvider.UpdateCode(substate.Output);
_stateProvider.UpdateCodeHash(env.CodeSource, codeHash, spec);
unspentGas -= codeDepositGasCost;
}
/// <summary>
/// Executes the <paramref name="entry" />.
/// </summary>
/// <param name="entry">Transaction entry to be executed inside the <see cref="VirtualMachine" />.</param>
/// <param name="stateUpdate"><see cref="Delta" /> to be used for execution environment construction</param>
/// <param name="txTracer">Tracer to extract the execution steps for debugging or analytics.</param>
/// <param name="readOnly">Defines whether the state should be reverted after the execution.</param>
/// <exception cref="TransactionCollisionException">Thrown when deployment address already has some code.</exception>
/// <exception cref="OutOfGasException">Thrown when not enough gas is available for deposit.</exception>
private void Execute(PublicEntry entry, StateUpdate stateUpdate, ITxTracer txTracer, bool readOnly)
{
var spec = _specProvider.GetSpec(stateUpdate.Number);
var(sender, recipient) = ExtractSenderAndRecipient(entry);
var isPrecompile = recipient.IsPrecompiled(spec);
var env = PrepareEnv(entry, sender, recipient, stateUpdate, isPrecompile);
var gasLimit = entry.GasLimit;
var intrinsicGas = CalculateIntrinsicGas(entry, spec);
if (_logger.IsEnabled(LogEventLevel.Verbose))
{
_logger.Verbose("Executing entry {entry}", entry);
}
if (!ValidateSender(entry, env, txTracer))
{
return;
}
if (!ValidateIntrinsicGas(entry, env, intrinsicGas, txTracer))
{
return;
}
if (!ValidateDeltaGasLimit(entry, env, txTracer))
{
return;
}
if (!_stateProvider.AccountExists(env.Sender))
{
if (env.GasPrice == UInt256.Zero)
{
_stateProvider.CreateAccount(env.Sender, UInt256.Zero);
}
}
if (!ValidateSenderBalance(entry, env, intrinsicGas, txTracer))
{
return;
}
if (!ValidateNonce(entry, env, txTracer))
{
return;
}
InitEntryExecution(env, gasLimit, spec, txTracer);
// we prepare two fields to track the amount of gas spent / left
var unspentGas = gasLimit - intrinsicGas;
var spentGas = gasLimit;
// the snapshots are needed to revert the subroutine state changes in case of an VM exception
var stateSnapshot = _stateProvider.TakeSnapshot();
var storageSnapshot = _storageProvider.TakeSnapshot();
// we subtract value from sender
// it will be added to recipient at the later stage (inside the VM)
_stateProvider.SubtractFromBalance(sender, env.Value, spec);
// we fail unless we succeed
var statusCode = StatusCode.Failure;
TransactionSubstate substate = null;
try
{
if (entry.IsValidDeploymentEntry)
{
PrepareContractAccount(env.CodeSource);
}
var executionType = entry.IsValidDeploymentEntry ? ExecutionType.Create : ExecutionType.Call;
using (var state = new VmState((long)unspentGas, env, executionType, isPrecompile, true, false))
{
substate = _virtualMachine.Run(state, txTracer);
unspentGas = (ulong)state.GasAvailable;
}
if (substate.ShouldRevert || substate.IsError)
{
if (_logger.IsEnabled(LogEventLevel.Verbose))
{
_logger.Verbose("Restoring state from before transaction");
}
_stateProvider.Restore(stateSnapshot);
_storageProvider.Restore(storageSnapshot);
}
else
{
if (entry.IsValidDeploymentEntry)
{
DeployCode(env, substate, ref unspentGas, spec);
}
DestroyAccounts(substate);
statusCode = StatusCode.Success;
}
spentGas = Refund(gasLimit, unspentGas, substate, env, spec);
}
catch (Exception ex) when(ex is EvmException || ex is OverflowException)
{
if (_logger.IsEnabled(LogEventLevel.Verbose))
{
_logger.Verbose($"EVM EXCEPTION: {ex.GetType().Name}");
}
_stateProvider.Restore(stateSnapshot);
_storageProvider.Restore(storageSnapshot);
}
if (_logger.IsEnabled(LogEventLevel.Verbose))
{
_logger.Verbose("Gas spent: " + spentGas);
}
var gasBeneficiary = stateUpdate.GasBeneficiary;
var wasBeneficiaryAccountDestroyed = statusCode != StatusCode.Failure &&
(substate?.DestroyList.Contains(gasBeneficiary) ?? false);
if (!wasBeneficiaryAccountDestroyed)
{
if (!_stateProvider.AccountExists(gasBeneficiary))
{
_stateProvider.CreateAccount(gasBeneficiary, spentGas * env.GasPrice);
}
else
{
_stateProvider.AddToBalance(gasBeneficiary, spentGas * env.GasPrice, spec);
}
}
if (!readOnly)
{
_storageProvider.Commit(txTracer.IsTracingState ? txTracer : null);
_stateProvider.Commit(spec, txTracer.IsTracingState ? txTracer : null);
stateUpdate.GasUsed += (long)spentGas;
}
else
{
_storageProvider.Reset();
_stateProvider.Reset();
}
if (txTracer.IsTracingReceipt)
{
if (statusCode == StatusCode.Failure)
{
txTracer.MarkAsFailed(env.CodeSource, (long)spentGas,
substate?.ShouldRevert ?? false ? substate.Output : Bytes.Empty, substate?.Error);
}
else
{
if (substate == null)
{
throw new InvalidOperationException("Substate should not be null after a successful VM run.");
}
txTracer.MarkAsSuccess(env.CodeSource, (long)spentGas, substate.Output,
substate.Logs.Any() ? substate.Logs.ToArray() : LogEntry.EmptyLogs);
}
}
}
protected void RunTest(VirtualMachineTest test)
{
TestContext.WriteLine($"Running {test.GetType().FullName}");
VirtualMachine machine = new VirtualMachine(_stateProvider, _storageProvider, _blockhashProvider, _specProvider, _logManager);
ExecutionEnvironment environment = new ExecutionEnvironment();
environment.Value = test.Execution.Value;
environment.CallDepth = 0;
environment.Sender = test.Execution.Caller;
environment.ExecutingAccount = test.Execution.Address;
BlockHeader header = new BlockHeader(
Keccak.OfAnEmptyString,
Keccak.OfAnEmptySequenceRlp,
test.Environment.CurrentCoinbase,
test.Environment.CurrentDifficulty,
test.Environment.CurrentNumber,
(long)test.Environment.CurrentGasLimit,
test.Environment.CurrentTimestamp, Bytes.Empty);
environment.CurrentBlock = header;
environment.GasPrice = test.Execution.GasPrice;
environment.InputData = test.Execution.Data;
environment.CodeInfo = new CodeInfo(test.Execution.Code);
environment.Originator = test.Execution.Origin;
foreach (KeyValuePair <Address, AccountState> accountState in test.Pre)
{
foreach (KeyValuePair <UInt256, byte[]> storageItem in accountState.Value.Storage)
{
_storageProvider.Set(new StorageCell(accountState.Key, storageItem.Key), storageItem.Value);
if (accountState.Key.Equals(test.Execution.Address))
{
_storageProvider.Set(new StorageCell(accountState.Key, storageItem.Key), storageItem.Value);
}
}
_stateProvider.UpdateCode(accountState.Value.Code);
_stateProvider.CreateAccount(accountState.Key, accountState.Value.Balance);
Keccak codeHash = _stateProvider.UpdateCode(accountState.Value.Code);
_stateProvider.UpdateCodeHash(accountState.Key, codeHash, Olympic.Instance);
for (int i = 0; i < accountState.Value.Nonce; i++)
{
_stateProvider.IncrementNonce(accountState.Key);
}
}
EvmState state = new EvmState((long)test.Execution.Gas, environment, ExecutionType.Transaction, true, false);
_storageProvider.Commit();
_stateProvider.Commit(Olympic.Instance);
TransactionSubstate substate = machine.Run(state, NullTxTracer.Instance);
if (test.Out == null)
{
Assert.NotNull(substate.Error);
return;
}
Assert.True(Bytes.AreEqual(test.Out, substate.Output),
$"Exp: {test.Out.ToHexString(true)} != Actual: {substate.Output.ToHexString(true)}");
Assert.AreEqual((long)test.Gas, state.GasAvailable, "gas available");
foreach (KeyValuePair <Address, AccountState> accountState in test.Post)
{
bool accountExists = _stateProvider.AccountExists(accountState.Key);
UInt256 balance = accountExists ? _stateProvider.GetBalance(accountState.Key) : 0;
UInt256 nonce = accountExists ? _stateProvider.GetNonce(accountState.Key) : 0;
Assert.AreEqual(accountState.Value.Balance, balance, $"{accountState.Key} Balance");
Assert.AreEqual(accountState.Value.Nonce, nonce, $"{accountState.Key} Nonce");
// TODO: not testing properly 0 balance accounts
if (accountExists)
{
byte[] code = _stateProvider.GetCode(accountState.Key);
Assert.AreEqual(accountState.Value.Code, code, $"{accountState.Key} Code");
}
foreach (KeyValuePair <UInt256, byte[]> storageItem in accountState.Value.Storage)
{
byte[] value = _storageProvider.Get(new StorageCell(accountState.Key, storageItem.Key));
Assert.True(Bytes.AreEqual(storageItem.Value, value),
$"Storage[{accountState.Key}_{storageItem.Key}] Exp: {storageItem.Value.ToHexString(true)} != Actual: {value.ToHexString(true)}");
}
}
}
private long Refund(long gasLimit, long unspentGas, TransactionSubstate substate, Address sender,
in UInt256 gasPrice, IReleaseSpec spec)
private void Execute(Transaction transaction, BlockHeader block, ITxTracer txTracer,
ExecutionOptions executionOptions)
{
bool eip658NotEnabled = !_specProvider.GetSpec(block.Number).IsEip658Enabled;
// restore is CallAndRestore - previous call, we will restore state after the execution
bool restore = (executionOptions & ExecutionOptions.Restore) == ExecutionOptions.Restore;
bool noValidation = (executionOptions & ExecutionOptions.NoValidation) == ExecutionOptions.NoValidation;
// commit - is for standard execute, we will commit thee state after execution
bool commit = (executionOptions & ExecutionOptions.Commit) == ExecutionOptions.Commit || eip658NotEnabled;
//!commit - is for build up during block production, we won't commit state after each transaction to support rollbacks
//we commit only after all block is constructed
bool notSystemTransaction = !transaction.IsSystem();
bool deleteCallerAccount = false;
IReleaseSpec spec = _specProvider.GetSpec(block.Number);
if (!notSystemTransaction)
{
spec = new SystemTransactionReleaseSpec(spec);
}
UInt256 value = transaction.Value;
if (!transaction.TryCalculatePremiumPerGas(block.BaseFeePerGas, out UInt256 premiumPerGas) && !noValidation)
{
TraceLogInvalidTx(transaction, "MINER_PREMIUM_IS_NEGATIVE");
QuickFail(transaction, block, txTracer, eip658NotEnabled, "miner premium is negative");
return;
}
UInt256 effectiveGasPrice =
transaction.CalculateEffectiveGasPrice(spec.IsEip1559Enabled, block.BaseFeePerGas);
long gasLimit = transaction.GasLimit;
byte[] machineCode = transaction.IsContractCreation ? transaction.Data : null;
byte[] data = transaction.IsMessageCall ? transaction.Data : Array.Empty <byte>();
Address?caller = transaction.SenderAddress;
if (_logger.IsTrace)
{
_logger.Trace($"Executing tx {transaction.Hash}");
}
if (caller is null)
{
TraceLogInvalidTx(transaction, "SENDER_NOT_SPECIFIED");
QuickFail(transaction, block, txTracer, eip658NotEnabled, "sender not specified");
return;
}
if (!noValidation && _stateProvider.IsInvalidContractSender(spec, caller))
{
TraceLogInvalidTx(transaction, "SENDER_IS_CONTRACT");
QuickFail(transaction, block, txTracer, eip658NotEnabled, "sender has deployed code");
return;
}
long intrinsicGas = IntrinsicGasCalculator.Calculate(transaction, spec);
if (_logger.IsTrace)
{
_logger.Trace($"Intrinsic gas calculated for {transaction.Hash}: " + intrinsicGas);
}
if (notSystemTransaction)
{
if (gasLimit < intrinsicGas)
{
TraceLogInvalidTx(transaction, $"GAS_LIMIT_BELOW_INTRINSIC_GAS {gasLimit} < {intrinsicGas}");
QuickFail(transaction, block, txTracer, eip658NotEnabled, "gas limit below intrinsic gas");
return;
}
if (!noValidation && gasLimit > block.GasLimit - block.GasUsed)
{
TraceLogInvalidTx(transaction,
$"BLOCK_GAS_LIMIT_EXCEEDED {gasLimit} > {block.GasLimit} - {block.GasUsed}");
QuickFail(transaction, block, txTracer, eip658NotEnabled, "block gas limit exceeded");
return;
}
}
if (!_stateProvider.AccountExists(caller))
{
// hacky fix for the potential recovery issue
if (transaction.Signature != null)
{
transaction.SenderAddress = _ecdsa.RecoverAddress(transaction, !spec.ValidateChainId);
}
if (caller != transaction.SenderAddress)
{
if (_logger.IsWarn)
{
_logger.Warn(
$"TX recovery issue fixed - tx was coming with sender {caller} and the now it recovers to {transaction.SenderAddress}");
}
caller = transaction.SenderAddress;
}
else
{
TraceLogInvalidTx(transaction, $"SENDER_ACCOUNT_DOES_NOT_EXIST {caller}");
if (!commit || noValidation || effectiveGasPrice == UInt256.Zero)
{
deleteCallerAccount = !commit || restore;
_stateProvider.CreateAccount(caller, UInt256.Zero);
}
}
if (caller is null)
{
throw new InvalidDataException(
$"Failed to recover sender address on tx {transaction.Hash} when previously recovered sender account did not exist.");
}
}
UInt256 senderReservedGasPayment = noValidation ? UInt256.Zero : (ulong)gasLimit * effectiveGasPrice;
if (notSystemTransaction)
{
UInt256 senderBalance = _stateProvider.GetBalance(caller);
if (!noValidation && ((ulong)intrinsicGas * effectiveGasPrice + value > senderBalance ||
senderReservedGasPayment + value > senderBalance))
{
TraceLogInvalidTx(transaction,
$"INSUFFICIENT_SENDER_BALANCE: ({caller})_BALANCE = {senderBalance}");
QuickFail(transaction, block, txTracer, eip658NotEnabled, "insufficient sender balance");
return;
}
if (!noValidation && spec.IsEip1559Enabled && !transaction.IsFree() &&
senderBalance < (UInt256)transaction.GasLimit * transaction.MaxFeePerGas + value)
{
TraceLogInvalidTx(transaction,
$"INSUFFICIENT_MAX_FEE_PER_GAS_FOR_SENDER_BALANCE: ({caller})_BALANCE = {senderBalance}, MAX_FEE_PER_GAS: {transaction.MaxFeePerGas}");
QuickFail(transaction, block, txTracer, eip658NotEnabled,
"insufficient MaxFeePerGas for sender balance");
return;
}
if (transaction.Nonce != _stateProvider.GetNonce(caller))
{
TraceLogInvalidTx(transaction,
$"WRONG_TRANSACTION_NONCE: {transaction.Nonce} (expected {_stateProvider.GetNonce(caller)})");
QuickFail(transaction, block, txTracer, eip658NotEnabled, "wrong transaction nonce");
return;
}
_stateProvider.IncrementNonce(caller);
}
_stateProvider.SubtractFromBalance(caller, senderReservedGasPayment, spec);
if (commit)
{
_stateProvider.Commit(spec, txTracer.IsTracingState ? txTracer : NullTxTracer.Instance);
}
long unspentGas = gasLimit - intrinsicGas;
long spentGas = gasLimit;
Snapshot snapshot = _worldState.TakeSnapshot();
_stateProvider.SubtractFromBalance(caller, value, spec);
byte statusCode = StatusCode.Failure;
TransactionSubstate substate = null;
Address?recipientOrNull = null;
try
{
Address?recipient =
transaction.GetRecipient(transaction.IsContractCreation ? _stateProvider.GetNonce(caller) : 0);
if (transaction.IsContractCreation)
{
// if transaction is a contract creation then recipient address is the contract deployment address
Address contractAddress = recipient;
PrepareAccountForContractDeployment(contractAddress !, spec);
}
if (recipient == null)
{
// this transaction is not a contract creation so it should have the recipient known and not null
throw new InvalidDataException("Recipient has not been resolved properly before tx execution");
}
recipientOrNull = recipient;
ExecutionEnvironment env = new();
env.TxExecutionContext = new TxExecutionContext(block, caller, effectiveGasPrice);
env.Value = value;
env.TransferValue = value;
env.Caller = caller;
env.CodeSource = recipient;
env.ExecutingAccount = recipient;
env.InputData = data ?? Array.Empty <byte>();
env.CodeInfo = machineCode == null
? _virtualMachine.GetCachedCodeInfo(_worldState, recipient, spec)
: new CodeInfo(machineCode);
ExecutionType executionType =
transaction.IsContractCreation ? ExecutionType.Create : ExecutionType.Call;
using (EvmState state =
new(unspentGas, env, executionType, true, snapshot, false))
{
if (spec.UseTxAccessLists)
{
state.WarmUp(transaction.AccessList); // eip-2930
}
if (spec.UseHotAndColdStorage)
{
state.WarmUp(caller); // eip-2929
state.WarmUp(recipient); // eip-2929
}
substate = _virtualMachine.Run(state, _worldState, txTracer);
unspentGas = state.GasAvailable;
if (txTracer.IsTracingAccess)
{
txTracer.ReportAccess(state.AccessedAddresses, state.AccessedStorageCells);
}
}
if (substate.ShouldRevert || substate.IsError)
{
if (_logger.IsTrace)
{
_logger.Trace("Restoring state from before transaction");
}
_worldState.Restore(snapshot);
}
else
{
// tks: there is similar code fo contract creation from init and from CREATE
// this may lead to inconsistencies (however it is tested extensively in blockchain tests)
if (transaction.IsContractCreation)
{
long codeDepositGasCost = CodeDepositHandler.CalculateCost(substate.Output.Length, spec);
if (unspentGas < codeDepositGasCost && spec.ChargeForTopLevelCreate)
{
throw new OutOfGasException();
}
if (CodeDepositHandler.CodeIsInvalid(spec, substate.Output))
{
throw new InvalidCodeException();
}
if (unspentGas >= codeDepositGasCost)
{
Keccak codeHash = _stateProvider.UpdateCode(substate.Output);
_stateProvider.UpdateCodeHash(recipient, codeHash, spec);
unspentGas -= codeDepositGasCost;
}
}
foreach (Address toBeDestroyed in substate.DestroyList)
{
if (_logger.IsTrace)
{
_logger.Trace($"Destroying account {toBeDestroyed}");
}
_storageProvider.ClearStorage(toBeDestroyed);
_stateProvider.DeleteAccount(toBeDestroyed);
if (txTracer.IsTracingRefunds)
{
txTracer.ReportRefund(RefundOf.Destroy(spec.IsEip3529Enabled));
}
}
statusCode = StatusCode.Success;
}
spentGas = Refund(gasLimit, unspentGas, substate, caller, effectiveGasPrice, spec);
}
catch (Exception ex) when(
ex is EvmException || ex is OverflowException) // TODO: OverflowException? still needed? hope not
{
if (_logger.IsTrace)
{
_logger.Trace($"EVM EXCEPTION: {ex.GetType().Name}");
}
_worldState.Restore(snapshot);
}
if (_logger.IsTrace)
{
_logger.Trace("Gas spent: " + spentGas);
}
Address gasBeneficiary = block.GasBeneficiary;
bool gasBeneficiaryNotDestroyed = substate?.DestroyList.Contains(gasBeneficiary) != true;
if (statusCode == StatusCode.Failure || gasBeneficiaryNotDestroyed)
{
if (notSystemTransaction)
{
UInt256 fees = (ulong)spentGas * premiumPerGas;
if (_stateProvider.AccountExists(gasBeneficiary))
{
_stateProvider.AddToBalance(gasBeneficiary, fees, spec);
}
else
{
_stateProvider.CreateAccount(gasBeneficiary, fees);
}
if (!transaction.IsFree() && spec.IsEip1559Enabled && spec.Eip1559FeeCollector is not null)
{
UInt256 burntFees = (ulong)spentGas * block.BaseFeePerGas;
if (!burntFees.IsZero)
{
if (_stateProvider.AccountExists(spec.Eip1559FeeCollector))
{
_stateProvider.AddToBalance(spec.Eip1559FeeCollector, burntFees, spec);
}
else
{
_stateProvider.CreateAccount(spec.Eip1559FeeCollector, burntFees);
}
}
}
}
}
if (restore)
{
_storageProvider.Reset();
_stateProvider.Reset();
if (deleteCallerAccount)
{
_stateProvider.DeleteAccount(caller);
}
else
{
_stateProvider.AddToBalance(caller, senderReservedGasPayment, spec);
if (notSystemTransaction)
{
_stateProvider.DecrementNonce(caller);
}
_stateProvider.Commit(spec);
}
}
else if (commit)
{
_storageProvider.Commit(txTracer.IsTracingState ? txTracer : NullStorageTracer.Instance);
_stateProvider.Commit(spec, txTracer.IsTracingState ? txTracer : NullStateTracer.Instance);
}
if (!noValidation && notSystemTransaction)
{
block.GasUsed += spentGas;
}
if (txTracer.IsTracingReceipt)
{
Keccak stateRoot = null;
if (eip658NotEnabled)
{
_stateProvider.RecalculateStateRoot();
stateRoot = _stateProvider.StateRoot;
}
if (statusCode == StatusCode.Failure)
{
txTracer.MarkAsFailed(recipientOrNull, spentGas,
(substate?.ShouldRevert ?? false) ? substate.Output.ToArray() : Array.Empty <byte>(),
substate?.Error, stateRoot);
}
else
{
txTracer.MarkAsSuccess(recipientOrNull, spentGas, substate.Output.ToArray(),
substate.Logs.Any() ? substate.Logs.ToArray() : Array.Empty <LogEntry>(), stateRoot);
}
}
}
