哪位大哥大姐帮我看看，怎么查火币的资金费率，调用参数，一直提示错误
也不知道问题在哪？刚学习不久

写法1：
function main() {
var res = exchange.IO(
"api",
"GET",
"/linear-swap-api/v1/swap_funding_rate","contract_code=BTC-USDT"
); //获取合约的资金费率

return res;
}

报错误：
Futures_OP 4: 400: {"timestamp":"2021-04-21T07:07:54.715+0000","status":400,"error":"Bad Request","message":"Required String parameter 'contract_code' is not present","path":"/linear-swap-api/v1/swap_funding_rate"}

写法2：
function main() {
var res = exchange.IO(
"api",
"GET",
"/linear-swap-api/v1/swap_funding_rate?contract_code=BTC-USDT"
); //获取合约的资金费率

return res;
}

报错误：
Futures_OP 4: map[err_code:1014 err_msg:This contract doesnt exist. status:error ts:1.618988994379e+12]