Python has type annotations but no type checking. The type checker you use for Python may have different soundness/decidability versus other type checkers. The

Python has type annotations but no type checking. The type checker you use for Python may have different soundness/decidability versus other type checkers. There's only one (official) TypeScript type checker, which works in only one way, and introduces both type annotations as well as syntax which compiles to JavaScript that's executed at runtime (enums, decorators).