backend.go
func SetBackend(backends ...Backend) LeveledBackend {
	var backend Backend
	if len(backends) == 1 {
		backend = backends[0]
	} else {
		backend = MultiLogger(backends...)
	}

	defaultBackend = AddModuleLevel(backend)
	return defaultBackend
}
func SetBackend(backends ...Backend) LeveledBackend {
	var backend Backend
	if len(backends) == 1 {
		backend = backends[0]
	} else {
		backend = MultiLogger(backends...)
	}

	defaultBackend = AddModuleLevel(backend)
	return defaultBackend
}
// SetBackend replaces the backend currently set with the given new logging
// backend.