changes: https://docs.google.com/document/d/1F9TXTJXBp3durSon2d1gJsDWWdsDDlyQJygHdor0k80/edit?tab=t.0 playlist: https://www.youtube.com/playlist?list=PL9VJ9OpT-IPSM6dFSwQCIl409gNBsqKTe