You are an expert in writing code in many different languages. Your goal is to perform code completion for the following code, keeping in mind the rest of the code and the file meta data.
    Metadata details:
    filename: unmarshal_error.go
    path of file: ./repos/awless/vendor/github.com/aws/aws-sdk-go/service/s3
    
    the code of the file until where you have to start completion: package s3

import (
	"encoding/xml"
	"fmt"
	"io"
	"io/ioutil"
	"net/http"
	"strings"

	"github.com/aws/aws-sdk-go/aws"
	"github.com/aws/aws-sdk-go/aws/awserr"
	"github.com/aws/aws-sdk-go/aws/request"
)

type xmlErrorResponse struct {
	XMLName xml.Name `xml:"Error"`
	Code    string   `xml:"Code"`
	Message string   `xml:"Message"`
}

func un
    
func unmarshalError(r *request.Request) {
	defer r.HTTPResponse.Body.Close()
	defer io.Copy(ioutil.Discard, r.HTTPResponse.Body)

	hostID := r.HTTPResponse.Header.Get("X-Amz-Id-2")

	// Bucket exists in a different region, and request needs
	// to be made to the correct region.
	if r.HTTPResponse.StatusCode == http.StatusMovedPermanently {
		r.Error = requestFailure{
			RequestFailure: awserr.NewRequestFailure(
				awserr.New("BucketRegionError",
					fmt.Sprintf("incorrect region, the bucket is not in '%s' region",
						aws.StringValue(r.Config.Region)),
					nil),
				r.HTTPResponse.StatusCode,
				r.RequestID,
			),
			hostID: hostID,
		}
		return
	}

	var errCode, errMsg string

	// Attempt to parse error from body if it is known
	resp := &xmlErrorResponse{}
	err := xml.NewDecoder(r.HTTPResponse.Body).Decode(resp)
	if err != nil && err != io.EOF {
		errCode = "SerializationError"
		errMsg = "failed to decode S3 XML error response"
	} else {
		errCode = resp.Code
		errMsg = resp.Message
		err = nil
	}

	// Fallback to status code converted to message if still no error code
	if len(errCode) == 0 {
		statusText := http.StatusText(r.HTTPResponse.StatusCode)
		errCode = strings.Replace(statusText, " ", "", -1)
		errMsg = statusText
	}

	r.Error = requestFailure{
		RequestFailure: awserr.NewRequestFailure(
			awserr.New(errCode, errMsg, err),
			r.HTTPResponse.StatusCode,
			r.RequestID,
		),
		hostID: hostID,
	}
}