Mayor Lori Lightfoot on Thursday lambasted as “clearly racist” and “deeply offensive” a tweet by the Chicago Teachers Union depicting an apparent cartoon version of her tied up, wearing a police uniform and being unmasked by the characters from the “Scooby-Doo” TV show. The tweet depicts the African American mayor bound with rope, surrounded by the white characters, who have taken a police officer mask off her head to reveal that the officer is actually Lightfoot. It’s a play on the scene at the end of each episode of the Hanna Barbera cartoon, when the team of youngsters would solve...