func (s *ScrollService) Highlight(highlight *Highlight) *ScrollService {
	s.ss = s.ss.Highlight(highlight)
	return s
}
Highlight allows to highlight search results on one or more fields
package elastic
import (
	"context"
	"fmt"
	"io"
	"net/http"
	"net/url"
	"strings"
	"sync"
	"github.com/olivere/elastic/v7/uritemplates"
)
const (
	DefaultScrollKeepAlive = "5m"
)
type ScrollService struct {
	client  *Client
	retrier Retrier
	pretty     *bool        
	human      *bool        
	errorTrace *bool        
	filterPath []string     
	headers    http.Header  
	indices           []string
	types             []string
	keepAlive         string
	body              interface{}
	ss                *SearchSource
	size              *int
	routing           string
	preference        string
	ignoreUnavailable *bool
	allowNoIndices    *bool
	expandWildcards   string
	maxResponseSize   int64
	mu       sync.RWMutex
	scrollId string
}
func NewScrollService(client *Client) *ScrollService {
	builder := &ScrollService{
		client:    client,
		ss:        NewSearchSource(),
		keepAlive: DefaultScrollKeepAlive,
	}
	return builder
}
func (s *ScrollService) Pretty(pretty bool) *ScrollService {
	s.pretty = &pretty
	return s
}
func (s *ScrollService) Human(human bool) *ScrollService {
	s.human = &human
	return s
}
func (s *ScrollService) ErrorTrace(errorTrace bool) *ScrollService {
	s.errorTrace = &errorTrace
	return s
}
func (s *ScrollService) FilterPath(filterPath ...string) *ScrollService {
	s.filterPath = filterPath
	return s
}
func (s *ScrollService) Header(name string, value string) *ScrollService {
	if s.headers == nil {
		s.headers = http.Header{}
	}
	s.headers.Add(name, value)
	return s
}
func (s *ScrollService) Headers(headers http.Header) *ScrollService {
	s.headers = headers
	return s
}
func (s *ScrollService) Retrier(retrier Retrier) *ScrollService {
	s.retrier = retrier
	return s
}
func (s *ScrollService) Index(indices ...string) *ScrollService {
	if s.indices == nil {
		s.indices = make([]string, 0)
	}
	s.indices = append(s.indices, indices...)
	return s
}
func (s *ScrollService) Type(types ...string) *ScrollService {
	if s.types == nil {
		s.types = make([]string, 0)
	}
	s.types = append(s.types, types...)
	return s
}
func (s *ScrollService) Scroll(keepAlive string) *ScrollService {
	s.keepAlive = keepAlive
	return s
}
func (s *ScrollService) KeepAlive(keepAlive string) *ScrollService {
	s.keepAlive = keepAlive
	return s
}
func (s *ScrollService) Size(size int) *ScrollService {
	s.size = &size
	return s
}