Method rpartition

crates/vm/src/builtins/str.rs:1234–1250

(&self, sep: PyStrRef, vm: &VirtualMachine)

    #[pymethod]
    fn rpartition(&self, sep: PyStrRef, vm: &VirtualMachine) -> PyResult {
        let (back, has_mid, front) = self.as_wtf8().py_partition(
            sep.as_wtf8(),
            || self.as_wtf8().rsplitn(2, sep.as_wtf8()),
            vm,
        )?;
        Ok((
            self.new_substr(front),
            if has_mid {
                sep
            } else {
                vm.ctx.empty_str.to_owned()
            },
            self.new_substr(back),
        )
            .to_pyobject(vm))
    }

    #[pymethod]
    fn istitle(&self) -> bool {