https://studygolang.com/articles/9467
https://www.jianshu.com/p/be3d9cdc680b
const ( StatusContinue = 100 StatusSwitchingProtocols = 101 StatusOK = 200 StatusCreated = 201 StatusAccepted = 202 StatusNonAuthoritativeInfo = 203 StatusNoContent = 204 StatusResetContent = 205 StatusPartialContent = 206 StatusMultipleChoices = 300 StatusMovedPermanently = 301 StatusFound = 302 StatusSeeOther = 303 StatusNotModified = 304 StatusUseProxy = 305 StatusTemporaryRedirect = 307 StatusBadRequest = 400 StatusUnauthorized = 401 StatusPaymentRequired = 402 StatusForbidden = 403 StatusNotFound = 404 StatusMethodNotAllowed = 405 StatusNotAcceptable = 406 StatusProxyAuthRequired = 407 StatusRequestTimeout = 408 StatusConflict = 409 StatusGone = 410 StatusLengthRequired = 411 StatusPreconditionFailed = 412 StatusRequestEntityTooLarge = 413 StatusRequestURITooLong = 414 StatusUnsupportedMediaType = 415 StatusRequestedRangeNotSatisfiable = 416 StatusExpectationFailed = 417 StatusTeapot = 418 StatusInternalServerError = 500 StatusNotImplemented = 501 StatusBadGateway = 502 StatusServiceUnavailable = 503 StatusGatewayTimeout = 504 StatusHTTPVersionNotSupported = 505 )