Return unique id of Blink binary sensor (#43942)

homeassistant/components/blink/binary_sensor.py

@@ -44,6 +44,11 @@ class BlinkBinarySensor(BinarySensorEntity):
         """Return the name of the blink sensor."""
         return self._name
 
+    @property
+    def unique_id(self):
+        """Return the unique id of the sensor."""
+        return self._unique_id
+
     @property
     def device_class(self):
         """Return the class of this device."""