Function anext

crates/vm/src/stdlib/builtins.rs:787–811

(
        aiter: PyObjectRef,
        default_value: OptionalArg<PyObjectRef>,
        vm: &VirtualMachine,
    )

    #[pyfunction]
    fn anext(
        aiter: PyObjectRef,
        default_value: OptionalArg<PyObjectRef>,
        vm: &VirtualMachine,
    ) -> PyResult {
        use crate::builtins::asyncgenerator::PyAnextAwaitable;

        // Check if object is an async iterator (has __anext__ method)
        if !aiter.class().has_attr(identifier!(vm, __anext__)) {
            return Err(vm.new_type_error(format!(
                "'{}' object is not an async iterator",
                aiter.class().name()
            )));
        }

        let awaitable = vm.call_method(&aiter, "__anext__", ())?;

        if let OptionalArg::Present(default) = default_value {
            Ok(PyAnextAwaitable::new(awaitable, default)
                .into_ref(&vm.ctx)
                .into())
        } else {
            Ok(awaitable)
        }
    }

    #[pyfunction]
    fn len(obj: PyObjectRef, vm: &VirtualMachine) -> PyResult<usize> {