here here :
About the Robot Dust:
The first time the aunt walked after him and turned on the light in his rooms - if there are other people on this planet, then the following information for them - the dust can remove an apartment in the dark!!! to
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Boy, you won’t believe it. He has optical dust sensors on his mouth and they are not even infrared. Try to drive it into a dark room, and after a week into the same room with light. The cleaning time is reduced by 2.