Function iter

crates/vm/src/stdlib/builtins.rs:765–779

(
        iter_target: PyObjectRef,
        sentinel: OptionalArg<PyObjectRef>,
        vm: &VirtualMachine,
    )

    #[pyfunction]
    fn iter(
        iter_target: PyObjectRef,
        sentinel: OptionalArg<PyObjectRef>,
        vm: &VirtualMachine,
    ) -> PyResult<PyIter> {
        if let OptionalArg::Present(sentinel) = sentinel {
            let callable = ArgCallable::try_from_object(vm, iter_target)?;
            let iterator = PyCallableIterator::new(callable, sentinel)
                .into_ref(&vm.ctx)
                .into();
            Ok(PyIter::new(iterator))
        } else {
            iter_target.get_iter(vm)
        }
    }

    #[pyfunction]
    fn aiter(iter_target: PyObjectRef, vm: &VirtualMachine) -> PyResult {