Method index

crates/vm/src/builtins/str.rs:1203–1206

(&self, args: FindArgs, vm: &VirtualMachine)

    #[pymethod]
    fn index(&self, args: FindArgs, vm: &VirtualMachine) -> PyResult<usize> {
        self._find(args, |r, s| Some(Self::_to_char_idx(r, r.find(s)?)))
            .ok_or_else(|| vm.new_value_error("substring not found"))
    }

    #[pymethod]
    fn rindex(&self, args: FindArgs, vm: &VirtualMachine) -> PyResult<usize> {