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: msearch.go
    path of file: ./repos/malice/vendor/github.com/olivere/elastic
    
    the code of the file until where you have to start completion: // Copyright 2012-present Oliver Eilhard. All rights reserved.
// Use of this source code is governed by a MIT-license.
// See http://olivere.mit-license.org/license.txt for details.

package elastic

import (
	"context"
	"encoding/json"
	"fmt"
	"net/url"
	"strings"
)

// MultiSearch executes one or more searches in one roundtrip.
type Multi
    
func (s *MultiSearchService) Do(ctx context.Context) (*MultiSearchResult, error) {
	// Build url
	path := "/_msearch"

	// Parameters
	params := make(url.Values)
	if s.pretty {
		params.Set("pretty", fmt.Sprintf("%v", s.pretty))
	}
	if v := s.maxConcurrentRequests; v != nil {
		params.Set("max_concurrent_searches", fmt.Sprintf("%v", *v))
	}
	if v := s.preFilterShardSize; v != nil {
		params.Set("pre_filter_shard_size", fmt.Sprintf("%v", *v))
	}

	// Set body
	var lines []string
	for _, sr := range s.requests {
		// Set default indices if not specified in the request
		if !sr.HasIndices() && len(s.indices) > 0 {
			sr = sr.Index(s.indices...)
		}

		header, err := json.Marshal(sr.header())
		if err != nil {
			return nil, err
		}
		body, err := sr.Body()
		if err != nil {
			return nil, err
		}
		lines = append(lines, string(header))
		lines = append(lines, body)
	}
	body := strings.Join(lines, "\n") + "\n" // add trailing \n

	// Get response
	res, err := s.client.PerformRequest(ctx, PerformRequestOptions{
		Method: "GET",
		Path:   path,
		Params: params,
		Body:   body,
	})
	if err != nil {
		return nil, err
	}

	// Return result
	ret := new(MultiSearchResult)
	if err := s.client.decoder.Decode(res.Body, ret); err != nil {
		return nil, err
	}
	return ret, nil
}