[TremendousJudge]

It's ridiculous. They should have made it an explicit part of the language. The interpreter knows about types already, it's crazy that they couldn't just let the user make the types explicit rather than implicit, and have the interpreter enforce that.

[mort96]

The interpreter knows types at runtime, not at parse/compile time. The interpreter already does a lot of dynamic type checking. It has a much stricter type system than e.g JavaScript; JavaScript will pretty much always convert operands to produce some result (even if it's just NaN or the string "object Object"), while Python will often just give you a type error.

The interpreter doesn't know about static types.

I agree that they should've made typing more a proper part of the language and not left it in this weird half-defined state of "standard syntax and some standard typing imports but undefined semantics". But it's not just a matter of enforcing existing types.