func (s *IndicesForcemergeService) Index(index ...string) *IndicesForcemergeService {
	if s.index == nil {
		s.index = make([]string, 0)
	}
	s.index = append(s.index, index...)
	return s
}
Index is a list of index names; use `_all` or empty string to perform
the operation on all indices.
package elastic
import (
	"fmt"
	"net/url"
	"strings"
	"gopkg.in/olivere/elastic.v3/uritemplates"
)
type IndicesForcemergeService struct {
	client             *Client
	pretty             bool
	index              []string
	allowNoIndices     *bool
	expandWildcards    string
	flush              *bool
	ignoreUnavailable  *bool
	maxNumSegments     interface{}
	onlyExpungeDeletes *bool
	operationThreading interface{}
	waitForMerge       *bool
}
func NewIndicesForcemergeService(client *Client) *IndicesForcemergeService {
	return &IndicesForcemergeService{
		client: client,
		index:  make([]string, 0),
	}
}