code: func (m *model) DeviceStatistics() map[string]stats.DeviceStatistics {
  	res := make(map[string]stats.DeviceStatistics)
  	for id := range m.cfg.Devices() {
  		res[id.String()] = m.deviceStatRef(id).GetStatistics()
  	}
  	return res
  }
docs: // DeviceStatistics returns statistics about each device