addrbook.go
func (a *AddrBook) Save() {
	log.Info("Saving AddrBook to file", "size", a.Size())
	a.saveToFile(a.filePath)
}
func (a *AddrBook) Save() {
	log.Info("Saving AddrBook to file", "size", a.Size())
	a.saveToFile(a.filePath)
}
// Save saves the book.