do so

expr infml

"I didn't say that!" "You did so" — "Я этого не говорил!" - "Нет, говорил"

"I didn't know about it" "You did so" — "Я не знал об этом" - "Нет, знал"

"I didn't do it" "You did so! You did so do it!" — "Я этого не делал" - "Нет, делал, делал!"