code: ********************timestamp: ********************signature: ********************curl --location '/train/openapi/v4/exchange-rates?from=CNY&to=USD%2CEUR' \
--header 'code: <api-key>' \
--header 'timestamp: <api-key>' \
--header 'signature: <api-key>'{
"code": 0,
"message": "Success",
"data": {
"USD": 0.138,
"EUR": 0.118
}
}