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: http.go
    path of file: ./repos/sliver/vendor/gopkg.in/jcmturner/gokrb5.v7/spnego
    
    the code of the file until where you have to start completion: package spnego

import (
	"bytes"
	"context"
	"encoding/base64"
	"errors"
	"fmt"
	"io"
	"io/ioutil"
	"net"
	"net/http"
	"net/http/cookiejar"
	"net/url"
	"strings"

	"gopkg.in/jcmturner/goidentity.v3"
	"gopkg.in/jcmturner/gokrb5.v7/client"
	"gopkg.in/jcmturner/gokrb5.v7/gssapi"
	"gopkg.in/jcmturner/gokrb5.v7/keytab"
	"gopkg.in/jcmturner/gokrb5.v7/krberror"
	"gopkg.in/jcmturner/gokrb5.v7/service"
	"gopkg.in/jcmturner/gokrb5.v7/types"
)

// Client side functionality //

// Client will negotiate authentication with a server using SPNEGO.
type Client struct {
	*http.Client
	krb5Client *client.Client
	spn        string
	reqs       []*http.Request
}

type redirectErr struct {
	reqTarget *http.Request
}

func (e redirectErr) Error() string {
	return fmt.Sprintf("redirect to %v", e.reqTarget.URL)
}

type teeReadCloser struct {
	io.Reader
	io.Closer
}

// NewClient returns an SPNEGO enabled HTTP client.
func NewClient(krb5Cl *client.Client, httpC
    
func (c *Client) Do(req *http.Request) (resp *http.Response, err error) {
	var body bytes.Buffer
	if req.Body != nil {
		// Use a tee reader to capture any body sent in case we have to replay it again
		teeR := io.TeeReader(req.Body, &body)
		teeRC := teeReadCloser{teeR, req.Body}
		req.Body = teeRC
	}
	resp, err = c.Client.Do(req)
	if err != nil {
		if ue, ok := err.(*url.Error); ok {
			if e, ok := ue.Err.(redirectErr); ok {
				// Picked up a redirect
				e.reqTarget.Header.Del(HTTPHeaderAuthRequest)
				c.reqs = append(c.reqs, e.reqTarget)
				if len(c.reqs) >= 10 {
					return resp, errors.New("stopped after 10 redirects")
				}
				if req.Body != nil {
					// Refresh the body reader so the body can be sent again
					e.reqTarget.Body = ioutil.NopCloser(&body)
				}
				return c.Do(e.reqTarget)
			}
		}
		return resp, err
	}
	if respUnauthorizedNegotiate(resp) {
		err := SetSPNEGOHeader(c.krb5Client, req, c.spn)
		if err != nil {
			return resp, err
		}
		if req.Body != nil {
			// Refresh the body reader so the body can be sent again
			req.Body = ioutil.NopCloser(&body)
		}
		return c.Do(req)
	}
	return resp, err
}