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: api_op_StartLifecyclePolicyPreview.go
    path of file: ./repos/aws-sdk-go-v2/service/ecr
    
    the code of the file until where you have to start completion: // Code generated by smithy-go-codegen DO NOT EDIT.

package ecr

import (
	"context"
	"fmt"
	awsmiddleware "github.com/aws/aws-sdk-go-v2/aws/middleware"
	"github.com/aws/aws-sdk-go-v2/service/ecr/types"
	"github.com/aws/smithy-go/middleware"
	smithyhttp "github.com/aws/smithy-go/transport/http"
)

// Starts a preview of a lifecycle policy for the specified repository. This
// allows you to see the results before associating the lifecycle policy with the
// repository.
func (c *Client) StartLifecyclePolicyPreview(ctx context.Context, params *StartLifecyclePolicyPreviewInput, optFns ...func(*Options)) (*StartLifecyclePolicyPreviewOutput, error) {
	if params == nil {
		params = &StartLifecyclePolicyPreviewInput{}
	}

	result, metadata, err := c.invokeOperation(ctx, "StartLifecyclePolicyPreview", params, optFns, c.addOperationStartLifecyclePolicyPreviewMiddlewares)
	if err != nil {
		return nil, err
	}

	out := result.(*StartLifecyclePolicyPreviewOutput)
	out.ResultMetadata = metadata
	return out, nil
}

type StartLifecyclePolicyPreviewInput struct {

	// The name of the repository to be evaluated.
	//
	// This member is required.
	RepositoryName *string

	// The policy to be 
    
func (c *Client) addOperationStartLifecyclePolicyPreviewMiddlewares(stack *middleware.Stack, options Options) (err error) {
	if err := stack.Serialize.Add(&setOperationInputMiddleware{}, middleware.After); err != nil {
		return err
	}
	err = stack.Serialize.Add(&awsAwsjson11_serializeOpStartLifecyclePolicyPreview{}, middleware.After)
	if err != nil {
		return err
	}
	err = stack.Deserialize.Add(&awsAwsjson11_deserializeOpStartLifecyclePolicyPreview{}, middleware.After)
	if err != nil {
		return err
	}
	if err := addProtocolFinalizerMiddlewares(stack, options, "StartLifecyclePolicyPreview"); err != nil {
		return fmt.Errorf("add protocol finalizers: %v", err)
	}

	if err = addlegacyEndpointContextSetter(stack, options); err != nil {
		return err
	}
	if err = addSetLoggerMiddleware(stack, options); err != nil {
		return err
	}
	if err = addClientRequestID(stack); err != nil {
		return err
	}
	if err = addComputeContentLength(stack); err != nil {
		return err
	}
	if err = addResolveEndpointMiddleware(stack, options); err != nil {
		return err
	}
	if err = addComputePayloadSHA256(stack); err != nil {
		return err
	}
	if err = addRetry(stack, options); err != nil {
		return err
	}
	if err = addRawResponseToMetadata(stack); err != nil {
		return err
	}
	if err = addRecordResponseTiming(stack); err != nil {
		return err
	}
	if err = addClientUserAgent(stack, options); err != nil {
		return err
	}
	if err = smithyhttp.AddErrorCloseResponseBodyMiddleware(stack); err != nil {
		return err
	}
	if err = smithyhttp.AddCloseResponseBodyMiddleware(stack); err != nil {
		return err
	}
	if err = addSetLegacyContextSigningOptionsMiddleware(stack); err != nil {
		return err
	}
	if err = addOpStartLifecyclePolicyPreviewValidationMiddleware(stack); err != nil {
		return err
	}
	if err = stack.Initialize.Add(newServiceMetadataMiddleware_opStartLifecyclePolicyPreview(options.Region), middleware.Before); err != nil {
		return err
	}
	if err = addRecursionDetection(stack); err != nil {
		return err
	}
	if err = addRequestIDRetrieverMiddleware(stack); err != nil {
		return err
	}
	if err = addResponseErrorMiddleware(stack); err != nil {
		return err
	}
	if err = addRequestResponseLogging(stack, options); err != nil {
		return err
	}
	if err = addDisableHTTPSMiddleware(stack, options); err != nil {
		return err
	}
	return nil
}