func (s *SACKScoreboard) Reset() {
	s.ranges = btree.New(defaultBtreeDegree)
	s.sacked = 0
}
Reset erases all known range information from the SACK scoreboard.
package tcp
import (
	"fmt"
	"strings"
	"github.com/google/btree"
	"github.com/google/netstack/tcpip/header"
	"github.com/google/netstack/tcpip/seqnum"
)
const (
	maxSACKBlocks = 100
	defaultBtreeDegree = 2
)
type SACKScoreboard struct {
	smss      uint16
	maxSACKED seqnum.Value
	sacked    seqnum.Size
	ranges    *btree.BTree
}
func NewSACKScoreboard(smss uint16, iss seqnum.Value) *SACKScoreboard {
	return &SACKScoreboard{
		smss:      smss,
		ranges:    btree.New(defaultBtreeDegree),
		maxSACKED: iss,
	}
}