Files
gocryptotrader/exchanges/coinut/coinut_websocket.go
Ryan O'Hara-Reid 63a9e9fcb1 Engine QA - Order update (#372)
Engine QA - Order update
2019-10-30 14:06:48 +11:00

724 lines
22 KiB
Go

package coinut
import (
"errors"
"fmt"
"net/http"
"strings"
"time"
"github.com/gorilla/websocket"
"github.com/thrasher-corp/gocryptotrader/common"
"github.com/thrasher-corp/gocryptotrader/common/crypto"
"github.com/thrasher-corp/gocryptotrader/currency"
exchange "github.com/thrasher-corp/gocryptotrader/exchanges"
"github.com/thrasher-corp/gocryptotrader/exchanges/asset"
"github.com/thrasher-corp/gocryptotrader/exchanges/order"
"github.com/thrasher-corp/gocryptotrader/exchanges/orderbook"
"github.com/thrasher-corp/gocryptotrader/exchanges/websocket/wshandler"
"github.com/thrasher-corp/gocryptotrader/exchanges/websocket/wsorderbook"
)
const (
coinutWebsocketURL = "wss://wsapi.coinut.com"
coinutWebsocketRateLimit = 30
)
var (
channels map[string]chan []byte
wsInstrumentMap instrumentMap
)
// NOTE for speed considerations
// wss://wsapi-as.coinut.com
// wss://wsapi-na.coinut.com
// wss://wsapi-eu.coinut.com
// WsConnect intiates a websocket connection
func (c *COINUT) WsConnect() error {
if !c.Websocket.IsEnabled() || !c.IsEnabled() {
return errors.New(wshandler.WebsocketNotEnabled)
}
var dialer websocket.Dialer
err := c.WebsocketConn.Dial(&dialer, http.Header{})
if err != nil {
return err
}
go c.WsHandleData()
if !wsInstrumentMap.IsLoaded() {
err = c.WsSetInstrumentList()
if err != nil {
return err
}
}
c.wsAuthenticate()
c.GenerateDefaultSubscriptions()
// define bi-directional communication
channels = make(map[string]chan []byte)
channels["hb"] = make(chan []byte, 1)
return nil
}
// WsHandleData handles read data
func (c *COINUT) WsHandleData() {
c.Websocket.Wg.Add(1)
defer func() {
c.Websocket.Wg.Done()
}()
for {
select {
case <-c.Websocket.ShutdownC:
return
default:
resp, err := c.WebsocketConn.ReadMessage()
if err != nil {
c.Websocket.ReadMessageErrors <- err
return
}
c.Websocket.TrafficAlert <- struct{}{}
if strings.HasPrefix(string(resp.Raw), "[") {
var incoming []wsResponse
err = common.JSONDecode(resp.Raw, &incoming)
if err != nil {
c.Websocket.DataHandler <- err
continue
}
for i := range incoming {
if incoming[i].Nonce > 0 {
c.WebsocketConn.AddResponseWithID(incoming[i].Nonce, resp.Raw)
break
}
var individualJSON []byte
individualJSON, err = common.JSONEncode(incoming[i])
if err != nil {
c.Websocket.DataHandler <- err
continue
}
c.wsProcessResponse(individualJSON)
}
} else {
var incoming wsResponse
err = common.JSONDecode(resp.Raw, &incoming)
if err != nil {
c.Websocket.DataHandler <- err
continue
}
c.wsProcessResponse(resp.Raw)
}
}
}
}
func (c *COINUT) wsProcessResponse(resp []byte) {
var incoming wsResponse
err := common.JSONDecode(resp, &incoming)
if err != nil {
c.Websocket.DataHandler <- err
return
}
switch incoming.Reply {
case "hb":
channels["hb"] <- resp
case "inst_tick":
var ticker WsTicker
err := common.JSONDecode(resp, &ticker)
if err != nil {
c.Websocket.DataHandler <- err
return
}
currencyPair := wsInstrumentMap.LookupInstrument(ticker.InstID)
c.Websocket.DataHandler <- wshandler.TickerData{
Exchange: c.Name,
Volume: ticker.Volume,
QuoteVolume: ticker.VolumeQuote,
High: ticker.HighestBuy,
Low: ticker.LowestSell,
Last: ticker.Last,
Timestamp: time.Unix(0, ticker.Timestamp),
AssetType: asset.Spot,
Pair: currency.NewPairFromFormattedPairs(currencyPair,
c.GetEnabledPairs(asset.Spot),
c.GetPairFormat(asset.Spot, true)),
}
case "inst_order_book":
var orderbooksnapshot WsOrderbookSnapshot
err := common.JSONDecode(resp, &orderbooksnapshot)
if err != nil {
c.Websocket.DataHandler <- err
return
}
err = c.WsProcessOrderbookSnapshot(&orderbooksnapshot)
if err != nil {
c.Websocket.DataHandler <- err
return
}
currencyPair := wsInstrumentMap.LookupInstrument(orderbooksnapshot.InstID)
c.Websocket.DataHandler <- wshandler.WebsocketOrderbookUpdate{
Exchange: c.GetName(),
Asset: asset.Spot,
Pair: currency.NewPairFromFormattedPairs(currencyPair,
c.GetEnabledPairs(asset.Spot),
c.GetPairFormat(asset.Spot, true)),
}
case "inst_order_book_update":
var orderbookUpdate WsOrderbookUpdate
err := common.JSONDecode(resp, &orderbookUpdate)
if err != nil {
c.Websocket.DataHandler <- err
return
}
err = c.WsProcessOrderbookUpdate(&orderbookUpdate)
if err != nil {
c.Websocket.DataHandler <- err
return
}
currencyPair := wsInstrumentMap.LookupInstrument(orderbookUpdate.InstID)
c.Websocket.DataHandler <- wshandler.WebsocketOrderbookUpdate{
Exchange: c.GetName(),
Asset: asset.Spot,
Pair: currency.NewPairFromFormattedPairs(currencyPair,
c.GetEnabledPairs(asset.Spot),
c.GetPairFormat(asset.Spot, true)),
}
case "inst_trade":
var tradeSnap WsTradeSnapshot
err := common.JSONDecode(resp, &tradeSnap)
if err != nil {
c.Websocket.DataHandler <- err
return
}
case "inst_trade_update":
var tradeUpdate WsTradeUpdate
err := common.JSONDecode(resp, &tradeUpdate)
if err != nil {
c.Websocket.DataHandler <- err
return
}
currencyPair := wsInstrumentMap.LookupInstrument(tradeUpdate.InstID)
c.Websocket.DataHandler <- wshandler.TradeData{
Timestamp: time.Unix(tradeUpdate.Timestamp, 0),
CurrencyPair: currency.NewPairFromFormattedPairs(currencyPair,
c.GetEnabledPairs(asset.Spot),
c.GetPairFormat(asset.Spot, true)),
AssetType: asset.Spot,
Exchange: c.GetName(),
Price: tradeUpdate.Price,
Side: tradeUpdate.Side,
}
default:
if incoming.Nonce > 0 {
c.WebsocketConn.AddResponseWithID(incoming.Nonce, resp)
return
}
c.Websocket.DataHandler <- fmt.Errorf("%v unhandled websocket response: %s", c.Name, resp)
}
}
// GetNonce returns a nonce for a required request
func (c *COINUT) GetNonce() int64 {
if c.Nonce.Get() == 0 {
c.Nonce.Set(time.Now().Unix())
} else {
c.Nonce.Inc()
}
return int64(c.Nonce.Get())
}
// WsSetInstrumentList fetches instrument list and propagates a local cache
func (c *COINUT) WsSetInstrumentList() error {
request := wsRequest{
Request: "inst_list",
SecType: strings.ToUpper(asset.Spot.String()),
Nonce: c.WebsocketConn.GenerateMessageID(false),
}
resp, err := c.WebsocketConn.SendMessageReturnResponse(request.Nonce, request)
if err != nil {
return err
}
var list WsInstrumentList
err = common.JSONDecode(resp, &list)
if err != nil {
return err
}
for curr, data := range list.Spot {
wsInstrumentMap.Seed(curr, data[0].InstID)
}
if len(wsInstrumentMap.GetInstrumentIDs()) == 0 {
return errors.New("instrument list failed to populate")
}
return nil
}
// WsProcessOrderbookSnapshot processes the orderbook snapshot
func (c *COINUT) WsProcessOrderbookSnapshot(ob *WsOrderbookSnapshot) error {
var bids []orderbook.Item
for i := range ob.Buy {
bids = append(bids, orderbook.Item{
Amount: ob.Buy[i].Volume,
Price: ob.Buy[i].Price,
})
}
var asks []orderbook.Item
for i := range ob.Sell {
asks = append(asks, orderbook.Item{
Amount: ob.Sell[i].Volume,
Price: ob.Sell[i].Price,
})
}
var newOrderBook orderbook.Base
newOrderBook.Asks = asks
newOrderBook.Bids = bids
newOrderBook.Pair = currency.NewPairFromFormattedPairs(
wsInstrumentMap.LookupInstrument(ob.InstID),
c.GetEnabledPairs(asset.Spot),
c.GetPairFormat(asset.Spot, true),
)
newOrderBook.AssetType = asset.Spot
newOrderBook.ExchangeName = c.GetName()
return c.Websocket.Orderbook.LoadSnapshot(&newOrderBook)
}
// WsProcessOrderbookUpdate process an orderbook update
func (c *COINUT) WsProcessOrderbookUpdate(update *WsOrderbookUpdate) error {
p := currency.NewPairFromFormattedPairs(
wsInstrumentMap.LookupInstrument(update.InstID),
c.GetEnabledPairs(asset.Spot),
c.GetPairFormat(asset.Spot, true),
)
bufferUpdate := &wsorderbook.WebsocketOrderbookUpdate{
CurrencyPair: p,
UpdateID: update.TransID,
AssetType: asset.Spot,
}
if strings.EqualFold(update.Side, order.Buy.Lower()) {
bufferUpdate.Bids = []orderbook.Item{{Price: update.Price, Amount: update.Volume}}
} else {
bufferUpdate.Asks = []orderbook.Item{{Price: update.Price, Amount: update.Volume}}
}
return c.Websocket.Orderbook.Update(bufferUpdate)
}
// GenerateDefaultSubscriptions Adds default subscriptions to websocket to be handled by ManageSubscriptions()
func (c *COINUT) GenerateDefaultSubscriptions() {
var channels = []string{"inst_tick", "inst_order_book"}
var subscriptions []wshandler.WebsocketChannelSubscription
enabledCurrencies := c.GetEnabledPairs(asset.Spot)
for i := range channels {
for j := range enabledCurrencies {
subscriptions = append(subscriptions, wshandler.WebsocketChannelSubscription{
Channel: channels[i],
Currency: enabledCurrencies[j],
})
}
}
c.Websocket.SubscribeToChannels(subscriptions)
}
// Subscribe sends a websocket message to receive data from the channel
func (c *COINUT) Subscribe(channelToSubscribe wshandler.WebsocketChannelSubscription) error {
subscribe := wsRequest{
Request: channelToSubscribe.Channel,
InstID: wsInstrumentMap.LookupID(c.FormatExchangeCurrency(channelToSubscribe.Currency,
asset.Spot).String()),
Subscribe: true,
Nonce: c.WebsocketConn.GenerateMessageID(false),
}
return c.WebsocketConn.SendMessage(subscribe)
}
// Unsubscribe sends a websocket message to stop receiving data from the channel
func (c *COINUT) Unsubscribe(channelToSubscribe wshandler.WebsocketChannelSubscription) error {
subscribe := wsRequest{
Request: channelToSubscribe.Channel,
InstID: wsInstrumentMap.LookupID(c.FormatExchangeCurrency(channelToSubscribe.Currency,
asset.Spot).String()),
Subscribe: false,
Nonce: c.WebsocketConn.GenerateMessageID(false),
}
resp, err := c.WebsocketConn.SendMessageReturnResponse(subscribe.Nonce, subscribe)
if err != nil {
return err
}
var response map[string]interface{}
err = common.JSONDecode(resp, &response)
if err != nil {
return err
}
if response["status"].([]interface{})[0] != "OK" {
return fmt.Errorf("%v unsubscribe failed for channel %v", c.Name, channelToSubscribe.Channel)
}
return nil
}
func (c *COINUT) wsAuthenticate() error {
if !c.GetAuthenticatedAPISupport(exchange.WebsocketAuthentication) {
return fmt.Errorf("%v AuthenticatedWebsocketAPISupport not enabled", c.Name)
}
timestamp := time.Now().Unix()
nonce := c.WebsocketConn.GenerateMessageID(false)
payload := fmt.Sprintf("%v|%v|%v", c.API.Credentials.ClientID, timestamp, nonce)
hmac := crypto.GetHMAC(crypto.HashSHA256, []byte(payload), []byte(c.API.Credentials.Key))
loginRequest := struct {
Request string `json:"request"`
Username string `json:"username"`
Nonce int64 `json:"nonce"`
Hmac string `json:"hmac_sha256"`
Timestamp int64 `json:"timestamp"`
}{
Request: "login",
Username: c.API.Credentials.ClientID,
Nonce: nonce,
Hmac: crypto.HexEncodeToString(hmac),
Timestamp: timestamp,
}
resp, err := c.WebsocketConn.SendMessageReturnResponse(loginRequest.Nonce, loginRequest)
if err != nil {
return err
}
var response map[string]interface{}
err = common.JSONDecode(resp, &response)
if err != nil {
return err
}
if response["status"].([]interface{})[0] != "OK" {
c.Websocket.SetCanUseAuthenticatedEndpoints(false)
return fmt.Errorf("%v failed to authenticate", c.Name)
}
c.Websocket.SetCanUseAuthenticatedEndpoints(true)
return nil
}
func (c *COINUT) wsGetAccountBalance() (*WsGetAccountBalanceResponse, error) {
if !c.Websocket.CanUseAuthenticatedEndpoints() {
return nil, fmt.Errorf("%v not authorised to submit order", c.Name)
}
accBalance := wsRequest{
Request: "user_balance",
Nonce: c.WebsocketConn.GenerateMessageID(false),
}
resp, err := c.WebsocketConn.SendMessageReturnResponse(accBalance.Nonce, accBalance)
if err != nil {
return nil, err
}
var response WsGetAccountBalanceResponse
err = common.JSONDecode(resp, &response)
if err != nil {
return nil, err
}
if response.Status[0] != "OK" {
return &response, fmt.Errorf("%v get account balance failed", c.Name)
}
return &response, nil
}
func (c *COINUT) wsSubmitOrder(order *WsSubmitOrderParameters) (*WsStandardOrderResponse, error) {
if !c.Websocket.CanUseAuthenticatedEndpoints() {
return nil, fmt.Errorf("%v not authorised to submit order", c.Name)
}
curr := c.FormatExchangeCurrency(order.Currency, asset.Spot).String()
var orderSubmissionRequest WsSubmitOrderRequest
orderSubmissionRequest.Request = "new_order"
orderSubmissionRequest.Nonce = c.WebsocketConn.GenerateMessageID(false)
orderSubmissionRequest.InstID = wsInstrumentMap.LookupID(curr)
orderSubmissionRequest.Qty = order.Amount
orderSubmissionRequest.Price = order.Price
orderSubmissionRequest.Side = string(order.Side)
if order.OrderID > 0 {
orderSubmissionRequest.OrderID = order.OrderID
}
resp, err := c.WebsocketConn.SendMessageReturnResponse(orderSubmissionRequest.Nonce, orderSubmissionRequest)
if err != nil {
return nil, err
}
var standardOrder WsStandardOrderResponse
standardOrder, err = c.wsStandardiseOrderResponse(resp)
if err != nil {
return nil, err
}
if standardOrder.Status[0] != "OK" {
return &standardOrder, fmt.Errorf("%v order submission failed. %v", c.Name, standardOrder)
}
if len(standardOrder.Reasons) > 0 && standardOrder.Reasons[0] != "" {
return &standardOrder, fmt.Errorf("%v order submission failed. %v", c.Name, standardOrder.Reasons[0])
}
return &standardOrder, nil
}
func (c *COINUT) wsStandardiseOrderResponse(resp []byte) (WsStandardOrderResponse, error) {
var response WsStandardOrderResponse
var incoming wsResponse
err := common.JSONDecode(resp, &incoming)
if err != nil {
return response, err
}
switch incoming.Reply {
case "order_accepted":
var orderAccepted WsOrderAcceptedResponse
err := common.JSONDecode(resp, &orderAccepted)
if err != nil {
return response, err
}
response = WsStandardOrderResponse{
InstID: orderAccepted.InstID,
Nonce: orderAccepted.Nonce,
OpenQty: orderAccepted.OpenQty,
OrderID: orderAccepted.OrderID,
OrderType: orderAccepted.Reply,
Price: orderAccepted.OrderPrice,
Qty: orderAccepted.Qty,
Side: orderAccepted.Side,
Status: orderAccepted.Status,
TransID: orderAccepted.TransID,
ClientOrdID: orderAccepted.ClientOrdID,
}
case "order_filled":
var orderFilled WsOrderFilledResponse
err := common.JSONDecode(resp, &orderFilled)
if err != nil {
return response, err
}
response = WsStandardOrderResponse{
InstID: orderFilled.Order.InstID,
Nonce: orderFilled.Nonce,
OpenQty: orderFilled.Order.OpenQty,
OrderID: orderFilled.Order.OrderID,
OrderType: orderFilled.Reply,
Price: orderFilled.Order.Price,
Qty: orderFilled.Order.Qty,
Side: orderFilled.Order.Side,
Status: orderFilled.Status,
TransID: orderFilled.TransID,
ClientOrdID: orderFilled.Order.ClientOrdID,
}
case "order_rejected":
var orderRejected WsOrderRejectedResponse
err := common.JSONDecode(resp, &orderRejected)
if err != nil {
return response, err
}
response = WsStandardOrderResponse{
InstID: orderRejected.InstID,
Nonce: orderRejected.Nonce,
OpenQty: orderRejected.OpenQty,
OrderID: orderRejected.OrderID,
OrderType: orderRejected.Reply,
Price: orderRejected.Price,
Qty: orderRejected.Qty,
Side: orderRejected.Side,
Status: orderRejected.Status,
TransID: orderRejected.TransID,
ClientOrdID: orderRejected.ClientOrdID,
Reasons: orderRejected.Reasons,
}
}
return response, nil
}
func (c *COINUT) wsSubmitOrders(orders []WsSubmitOrderParameters) ([]WsStandardOrderResponse, []error) {
var errors []error
var ordersResponse []WsStandardOrderResponse
if !c.Websocket.CanUseAuthenticatedEndpoints() {
errors = append(errors, fmt.Errorf("%v not authorised to submit orders", c.Name))
return nil, errors
}
orderRequest := WsSubmitOrdersRequest{}
for i := range orders {
curr := c.FormatExchangeCurrency(orders[i].Currency, asset.Spot).String()
orderRequest.Orders = append(orderRequest.Orders,
WsSubmitOrdersRequestData{
Qty: orders[i].Amount,
Price: orders[i].Price,
Side: string(orders[i].Side),
InstID: wsInstrumentMap.LookupID(curr),
ClientOrdID: i + 1,
})
}
orderRequest.Nonce = c.WebsocketConn.GenerateMessageID(false)
orderRequest.Request = "new_orders"
resp, err := c.WebsocketConn.SendMessageReturnResponse(orderRequest.Nonce, orderRequest)
if err != nil {
errors = append(errors, err)
return nil, errors
}
var incoming []interface{}
err = common.JSONDecode(resp, &incoming)
if err != nil {
errors = append(errors, err)
return nil, errors
}
for i := range incoming {
var individualJSON []byte
individualJSON, err = common.JSONEncode(incoming[i])
if err != nil {
errors = append(errors, err)
continue
}
standardOrder, err := c.wsStandardiseOrderResponse(individualJSON)
if err != nil {
errors = append(errors, err)
continue
}
if standardOrder.Status[0] != "OK" {
errors = append(errors, fmt.Errorf("%v order submission failed. %v", c.Name, standardOrder))
continue
}
if len(standardOrder.Reasons) > 0 && standardOrder.Reasons[0] != "" {
errors = append(errors, fmt.Errorf("%v order submission failed for currency %v and orderID %v, message %v ",
c.Name,
wsInstrumentMap.LookupInstrument(standardOrder.InstID),
standardOrder.OrderID,
standardOrder.Reasons[0]))
continue
}
ordersResponse = append(ordersResponse, standardOrder)
}
return ordersResponse, errors
}
func (c *COINUT) wsGetOpenOrders(p currency.Pair) error {
if !c.Websocket.CanUseAuthenticatedEndpoints() {
return fmt.Errorf("%v not authorised to get open orders", c.Name)
}
curr := c.FormatExchangeCurrency(p, asset.Spot).String()
var openOrdersRequest WsGetOpenOrdersRequest
openOrdersRequest.Request = "user_open_orders"
openOrdersRequest.Nonce = c.WebsocketConn.GenerateMessageID(false)
openOrdersRequest.InstID = wsInstrumentMap.LookupID(curr)
resp, err := c.WebsocketConn.SendMessageReturnResponse(openOrdersRequest.Nonce, openOrdersRequest)
if err != nil {
return err
}
var response map[string]interface{}
err = common.JSONDecode(resp, &response)
if err != nil {
return err
}
if response["status"].([]interface{})[0] != "OK" {
return fmt.Errorf("%v get open orders failed for currency %v",
c.Name,
p)
}
return nil
}
func (c *COINUT) wsCancelOrder(cancellation WsCancelOrderParameters) error {
if !c.Websocket.CanUseAuthenticatedEndpoints() {
return fmt.Errorf("%v not authorised to cancel order", c.Name)
}
currency := c.FormatExchangeCurrency(cancellation.Currency, asset.Spot).String()
var cancellationRequest WsCancelOrderRequest
cancellationRequest.Request = "cancel_order"
cancellationRequest.InstID = wsInstrumentMap.LookupID(currency)
cancellationRequest.OrderID = cancellation.OrderID
cancellationRequest.Nonce = c.WebsocketConn.GenerateMessageID(false)
resp, err := c.WebsocketConn.SendMessageReturnResponse(cancellationRequest.Nonce, cancellationRequest)
if err != nil {
return err
}
var response map[string]interface{}
err = common.JSONDecode(resp, &response)
if err != nil {
return err
}
if response["status"].([]interface{})[0] != "OK" {
return fmt.Errorf("%v order cancellation failed for currency %v and orderID %v, message %v",
c.Name,
cancellation.Currency,
cancellation.OrderID,
response["status"])
}
return nil
}
func (c *COINUT) wsCancelOrders(cancellations []WsCancelOrderParameters) (*WsCancelOrdersResponse, []error) {
var errors []error
if !c.Websocket.CanUseAuthenticatedEndpoints() {
return nil, errors
}
cancelOrderRequest := WsCancelOrdersRequest{}
for i := range cancellations {
currency := c.FormatExchangeCurrency(cancellations[i].Currency, asset.Spot).String()
cancelOrderRequest.Entries = append(cancelOrderRequest.Entries, WsCancelOrdersRequestEntry{
InstID: wsInstrumentMap.LookupID(currency),
OrderID: cancellations[i].OrderID,
})
}
cancelOrderRequest.Request = "cancel_orders"
cancelOrderRequest.Nonce = c.WebsocketConn.GenerateMessageID(false)
resp, err := c.WebsocketConn.SendMessageReturnResponse(cancelOrderRequest.Nonce, cancelOrderRequest)
if err != nil {
return nil, []error{err}
}
var response WsCancelOrdersResponse
err = common.JSONDecode(resp, &response)
if err != nil {
return nil, []error{err}
}
if response.Status[0] != "OK" {
return &response, []error{err}
}
for i := range response.Results {
if response.Results[i].Status != "OK" {
errors = append(errors, fmt.Errorf("%v order cancellation failed for currency %v and orderID %v, message %v",
c.Name,
wsInstrumentMap.LookupInstrument(response.Results[i].InstID),
response.Results[i].OrderID,
response.Results[i].Status))
}
}
return &response, errors
}
func (c *COINUT) wsGetTradeHistory(p currency.Pair, start, limit int64) error {
if !c.Websocket.CanUseAuthenticatedEndpoints() {
return fmt.Errorf("%v not authorised to get trade history", c.Name)
}
curr := c.FormatExchangeCurrency(p, asset.Spot).String()
var request WsTradeHistoryRequest
request.Request = "trade_history"
request.InstID = wsInstrumentMap.LookupID(curr)
request.Nonce = c.WebsocketConn.GenerateMessageID(false)
request.Start = start
request.Limit = limit
resp, err := c.WebsocketConn.SendMessageReturnResponse(request.Nonce, request)
if err != nil {
return err
}
var response map[string]interface{}
err = common.JSONDecode(resp, &response)
if err != nil {
return err
}
if response["status"].([]interface{})[0] != "OK" {
return fmt.Errorf("%v get trade history failed for %v",
c.Name,
request)
}
return nil
}