docs: def device_state_attributes(self):
          """Return the state attributes of the device."""
          attr = {}
          attr['active_time'] = self.smartplug.active_time
          attr['voltage'] = self.smartplug.voltage
          attr['active_time'] = self.smartplug.active_time
          attr['weekly_energy_total'] = self.smartplug.weekly_energy_total
          attr['monthly_energy_total'] = self.smartplug.monthly_energy_total
          attr['yearly_energy_total'] = self.smartplug.yearly_energy_total
          return attr