func (s *MgetService) Source() (interface{}, error) {
	source := make(map[string]interface{})
	items := make([]interface{}, len(s.items))
	for i, item := range s.items {
		src, err := item.Source()
		if err != nil {
			return nil, err
		}
		items[i] = src
	}
	source["docs"] = items
	return source, nil
}
Source returns the request body, which will be serialized into JSON.
package elastic
import (
	"context"
	"fmt"
	"net/url"
	"strings"
)
type MgetService struct {
	client       *Client
	pretty       bool
	preference   string
	realtime     *bool
	refresh      string
	routing      string
	storedFields []string
	items        []*MultiGetItem
}
func NewMgetService(client *Client) *MgetService {
	builder := &MgetService{
		client: client,
	}
	return builder
}
func (s *MgetService) Preference(preference string) *MgetService {
	s.preference = preference
	return s
}
func (s *MgetService) Refresh(refresh string) *MgetService {
	s.refresh = refresh
	return s
}
func (s *MgetService) Realtime(realtime bool) *MgetService {
	s.realtime = &realtime
	return s
}
func (s *MgetService) Routing(routing string) *MgetService {
	s.routing = routing
	return s
}
func (s *MgetService) StoredFields(storedFields ...string) *MgetService {
	s.storedFields = append(s.storedFields, storedFields...)
	return s
}
func (s *MgetService) Pretty(pretty bool) *MgetService {
	s.pretty = pretty
	return s
}
func (s *MgetService) Add(items ...*MultiGetItem) *MgetService {
	s.items = append(s.items, items...)
	return s
}