func (n *Node) setNext(key string, value *Node) {
	if n.next == nil {
		n.next = make(map[string]*Node)
	}
	n.next[key] = value
}
setNext adds a subnode.
package nodetree
import (
	"strings"
)
type Node struct {
	Key      string
	LeaseID  int64
	next     map[string]*Node
	HasValue bool
}
func NewNode(key string, leaseID int64) *Node {
	return &Node{Key: key, LeaseID: leaseID}
}
func (n *Node) Count() int {
	if n.next == nil {
		return 0
	}
	return len(n.next)
}
func (n *Node) Children() map[string]*Node {
	return n.next
}
func (n *Node) getNext(key string) *Node {
	if n.next == nil {
		return nil
	}
	return n.next[key]
}