'Return the icon for the sensor.'

@property
def icon(self):

    if ((self._sensor == 'battery_level') and (self._state is not None)):
        rounded_level = round(int(self._state), (-1))
        returning_icon = 'mdi:battery'
        if (rounded_level < 10):
            returning_icon = 'mdi:battery-outline'
        elif (self._state == 100):
            returning_icon = 'mdi:battery'
        else:
            returning_icon = 'mdi:battery-{}'.format(str(rounded_level))
        return returning_icon
    return ICON_MAP.get(self._sensor, 'mdi:eye')
