Remove TODO for interface support since they are now supported

trans/stdlib/__init__.py

@@ -15,8 +15,6 @@ U = TypeVar("U")
 V = TypeVar("V")
 
 
-# TODO: really, these should work as interfaces, on a duck-typing basis. it's gonna be a hell of a ride to implement
-# unification for this
 class HasLen(Protocol):
     def __len__(self) -> int: ...
 
@@ -39,6 +37,8 @@ class str:
     def __add__(self, other: Self) -> Self: ...
     def __mul__(self, other: int) -> Self: ...
 
+assert len("a")
+
 class bytes:
     def decode(self, encoding: str) -> str: ...
     def __len__(self) -> int: ...