Method try_upgrade

crates/vm/src/builtins/weakproxy.rs:78–80

(&self, vm: &VirtualMachine)

))]
impl PyWeakProxy {
    fn try_upgrade(&self, vm: &VirtualMachine) -> PyResult {
        self.weak.upgrade().ok_or_else(|| new_reference_error(vm))
    }

    #[pymethod]
    fn __str__(zelf: &Py<Self>, vm: &VirtualMachine) -> PyResult<PyStrRef> {