func (s *Segment) Cursor() Cursor {
	return Cursor{s: s}
}
Cursor returns a proxy with concurrent access to a Segment
package segment
import (
	"bytes"
	"io"
	"net/http"
	"time"
)
const (
	cacheSegment = "max-age=180, public"
	cachePart    = "max-age=15, public"
)
type Cursor struct {
	s *Segment
}