func (w *WriteBuffer) WriteUint64(n uint64) {
	if b := w.reserve(8); b != nil {
		binary.BigEndian.PutUint64(b, n)
	}
}
func (w *WriteBuffer) WriteUint64(n uint64) {
	if b := w.reserve(8); b != nil {
		binary.BigEndian.PutUint64(b, n)
	}
}
// WriteUint64 writes a big endian uint64 to the buffer