func (c *Client) newResponse(res *http.Response, maxBodySize int64) (*Response, error) {
	r := &Response{
		StatusCode:          res.StatusCode,
		Header:              res.Header,
		DeprecationWarnings: res.Header["Warning"],
	}
	if res.Body != nil {
		body := io.Reader(res.Body)
		if maxBodySize > 0 {
			if res.ContentLength > maxBodySize {
				return nil, ErrResponseSize
			}
			body = io.LimitReader(body, maxBodySize+1)
		}
		slurp, err := ioutil.ReadAll(body)
		if err != nil {
			return nil, err
		}
		if maxBodySize > 0 && int64(len(slurp)) > maxBodySize {
			return nil, ErrResponseSize
		}
		if len(slurp) > 0 {
			r.Body = json.RawMessage(slurp)
		}
	}
	return r, nil
}
newResponse creates a new response from the HTTP response.
package elastic
import (
	"encoding/json"
	"errors"
	"io"
	"io/ioutil"
	"net/http"
)
var (
	ErrResponseSize = errors.New("elastic: response size too large")
)
type Response struct {
	StatusCode int
	Header http.Header
	Body json.RawMessage
	DeprecationWarnings []string
}