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: rp.go
    path of file: ./repos/teller/vendor/github.com/Azure/go-autorest/autorest/azure
    
    the code of the file until where you have to start completion: // Copyright 2017 Microsoft Corporation
//
//  Licensed under the Apache License, Version 2.0 (the "License");
//  you may not use this file except in compliance with the License.
//  You may obtain a copy of the License at
//
//      http://www.apache.org/licenses/LICENSE-2.0
//
//  Unless required by applicable law or agreed to in writing, software
//  distributed under the License is distributed on an "AS IS" BASIS,
//  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
//  See the License for the specific language governing permissions and
//  limitations under the License.

package azure

import (
	"errors"
	"fmt"
	"net/http"
	"net/url"
	"strings"
	"time"

	"github.com/Azure/go-autorest/autorest"
)

// DoRetryWithRegistration tries to register the resource provider in case it is unregistered.
// It also handles request retries
func DoRetryWithRegistration(client autorest.Client) autorest.SendDecorator {
	return func(s autorest.Sender) autorest.Sender {
		return autorest.SenderFunc(func(r *http.Request) (resp *http.Response, err error) {
			rr := autorest.NewRetriableRequest(r)
			for currentAttempt := 0; currentAttempt < client.RetryAttempts; currentAttempt++ {
				err = rr.Prepare()
				if err != nil {
					return resp, err
				}

				resp, err = autorest.SendWithSender(s, rr.Request(),
					autorest.DoRetryForStatusCodes(client.RetryAttempts, client.RetryDuration, autorest.StatusCodesForRetry...),
				)
				if err != nil {
					return resp, err
				}

				if resp.StatusCode != http.StatusConflict || client.SkipResourceProviderRegistration {
					return resp, err
				}

				var re RequestError
				if strings.Contains(r.Header.Get("Content-Type"), "xml") {
					// XML errors (e.g. Storage Data Plane) only return the inner object
					err = autorest.Respond(resp, autorest.ByUnmarshallingXML(&re.ServiceError))
				} else {
					err = autorest.Respond(resp, autorest.ByUnmarshallingJSON(&re))
				}

				if err != nil {
					return resp, err
				}
				err = re

				if re.ServiceError != nil && re.ServiceError.Code == "MissingSubscriptionRegistration" {
					regErr := register(client, r, re)
					if regErr != nil {
						return resp, fmt.Errorf("failed auto registering Resource Provider: %s. Original error: %s", regErr, err)
					}
				}
			}
			return resp, err
		})
	}
}

func getProvider(re Reque
    
func register(client autorest.Client, originalReq *http.Request, re RequestError) error {
	subID := getSubscription(originalReq.URL.Path)
	if subID == "" {
		return errors.New("missing parameter subscriptionID to register resource provider")
	}
	providerName, err := getProvider(re)
	if err != nil {
		return fmt.Errorf("missing parameter provider to register resource provider: %s", err)
	}
	newURL := url.URL{
		Scheme: originalReq.URL.Scheme,
		Host:   originalReq.URL.Host,
	}

	// taken from the resources SDK
	// with almost identical code, this sections are easier to mantain
	// It is also not a good idea to import the SDK here
	// https://github.com/Azure/azure-sdk-for-go/blob/9f366792afa3e0ddaecdc860e793ba9d75e76c27/arm/resources/resources/providers.go#L252
	pathParameters := map[string]interface{}{
		"resourceProviderNamespace": autorest.Encode("path", providerName),
		"subscriptionId":            autorest.Encode("path", subID),
	}

	const APIVersion = "2016-09-01"
	queryParameters := map[string]interface{}{
		"api-version": APIVersion,
	}

	preparer := autorest.CreatePreparer(
		autorest.AsPost(),
		autorest.WithBaseURL(newURL.String()),
		autorest.WithPathParameters("/subscriptions/{subscriptionId}/providers/{resourceProviderNamespace}/register", pathParameters),
		autorest.WithQueryParameters(queryParameters),
	)

	req, err := preparer.Prepare(&http.Request{})
	if err != nil {
		return err
	}
	req = req.WithContext(originalReq.Context())

	resp, err := autorest.SendWithSender(client, req,
		autorest.DoRetryForStatusCodes(client.RetryAttempts, client.RetryDuration, autorest.StatusCodesForRetry...),
	)
	if err != nil {
		return err
	}

	type Provider struct {
		RegistrationState *string `json:"registrationState,omitempty"`
	}
	var provider Provider

	err = autorest.Respond(
		resp,
		WithErrorUnlessStatusCode(http.StatusOK),
		autorest.ByUnmarshallingJSON(&provider),
		autorest.ByClosing(),
	)
	if err != nil {
		return err
	}

	// poll for registered provisioning state
	registrationStartTime := time.Now()
	for err == nil && (client.PollingDuration == 0 || (client.PollingDuration != 0 && time.Since(registrationStartTime) < client.PollingDuration)) {
		// taken from the resources SDK
		// https://github.com/Azure/azure-sdk-for-go/blob/9f366792afa3e0ddaecdc860e793ba9d75e76c27/arm/resources/resources/providers.go#L45
		preparer := autorest.CreatePreparer(
			autorest.AsGet(),
			autorest.WithBaseURL(newURL.String()),
			autorest.WithPathParameters("/subscriptions/{subscriptionId}/providers/{resourceProviderNamespace}", pathParameters),
			autorest.WithQueryParameters(queryParameters),
		)
		req, err = preparer.Prepare(&http.Request{})
		if err != nil {
			return err
		}
		req = req.WithContext(originalReq.Context())

		resp, err := autorest.SendWithSender(client, req,
			autorest.DoRetryForStatusCodes(client.RetryAttempts, client.RetryDuration, autorest.StatusCodesForRetry...),
		)
		if err != nil {
			return err
		}

		err = autorest.Respond(
			resp,
			WithErrorUnlessStatusCode(http.StatusOK),
			autorest.ByUnmarshallingJSON(&provider),
			autorest.ByClosing(),
		)
		if err != nil {
			return err
		}

		if provider.RegistrationState != nil &&
			*provider.RegistrationState == "Registered" {
			break
		}

		delayed := autorest.DelayWithRetryAfter(resp, originalReq.Context().Done())
		if !delayed && !autorest.DelayForBackoff(client.PollingDelay, 0, originalReq.Context().Done()) {
			return originalReq.Context().Err()
		}
	}
	if client.PollingDuration != 0 && !(time.Since(registrationStartTime) < client.PollingDuration) {
		return errors.New("polling for resource provider registration has exceeded the polling duration")
	}
	return err
}