func (l *pingPacketList) InsertAfter(b, e *pingPacket) {
	a := pingPacketElementMapper{}.linkerFor(b).Next()
	pingPacketElementMapper{}.linkerFor(e).SetNext(a)
	pingPacketElementMapper{}.linkerFor(e).SetPrev(b)
	pingPacketElementMapper{}.linkerFor(b).SetNext(e)
	if a != nil {
		pingPacketElementMapper{}.linkerFor(a).SetPrev(e)
	} else {
		l.tail = e
	}
}
InsertAfter inserts e after b.
package ping
type pingPacketElementMapper struct{}
func (pingPacketElementMapper) linkerFor(elem *pingPacket) *pingPacket { return elem }
type pingPacketList struct {
	head *pingPacket
	tail *pingPacket
}
func (l *pingPacketList) Reset() {
	l.head = nil
	l.tail = nil
}
func (l *pingPacketList) Empty() bool {
	return l.head == nil
}
func (l *pingPacketList) Front() *pingPacket {
	return l.head
}
func (l *pingPacketList) Back() *pingPacket {
	return l.tail
}
func (l *pingPacketList) PushFront(e *pingPacket) {
	pingPacketElementMapper{}.linkerFor(e).SetNext(l.head)
	pingPacketElementMapper{}.linkerFor(e).SetPrev(nil)
	if l.head != nil {
		pingPacketElementMapper{}.linkerFor(l.head).SetPrev(e)
	} else {
		l.tail = e
	}
	l.head = e
}
func (l *pingPacketList) PushBack(e *pingPacket) {
	pingPacketElementMapper{}.linkerFor(e).SetNext(nil)
	pingPacketElementMapper{}.linkerFor(e).SetPrev(l.tail)
	if l.tail != nil {
		pingPacketElementMapper{}.linkerFor(l.tail).SetNext(e)
	} else {
		l.head = e
	}
	l.tail = e
}
func (l *pingPacketList) PushBackList(m *pingPacketList) {
	if l.head == nil {
		l.head = m.head
		l.tail = m.tail
	} else if m.head != nil {
		pingPacketElementMapper{}.linkerFor(l.tail).SetNext(m.head)
		pingPacketElementMapper{}.linkerFor(m.head).SetPrev(l.tail)
		l.tail = m.tail
	}
	m.head = nil
	m.tail = nil
}