You are an expert in writing code in many different languages. Your goal is to perform code completion for the following code, keeping in mind the rest of the code and the file meta data.
    Metadata details:
    filename: suggestion.rs
    path of file: ./repos/RustPython/vm/src
    
    the code of the file until where you have to start completion: use crate::{
    builtins::{PyStr, PyStrRef},
    exceptions::types::PyBaseExceptionRef,
    sliceable::SliceableSequenceOp,
    AsObject, Py, PyObjectRef, VirtualMachine,
};
use rustpython_common::str::levenshtein::{levenshtein_distance, MOVE_COST};
use std::iter::ExactSizeIterator;

const MAX_CANDIDATE_ITEMS: usize = 750;

fn calculate_suggestions<'a>(
    dir_iter: impl ExactSizeIterator<Item = &'a PyObjectRef>,
    name: &PyObjectRef,
) -> Option<PyStrRef> {
    if dir_iter.len() >= MAX_CANDIDATE_ITEMS {
        return None;
    }

    let mut suggestion: Option<&Py<PyStr>> = None;
    let mut suggestion_distance = usize::MAX;
    let name = name.downcast_ref::<PyStr>()?;

    for item in dir_iter {
        let item_name = item.downcast_re
    
pub fn offer_suggestions(exc: &PyBaseExceptionRef, vm: &VirtualMachine) -> Option<PyStrRef> {
    if exc.class().is(vm.ctx.exceptions.attribute_error) {
        let name = exc.as_object().get_attr("name", vm).unwrap();
        let obj = exc.as_object().get_attr("obj", vm).unwrap();

        calculate_suggestions(vm.dir(Some(obj)).ok()?.borrow_vec().iter(), &name)
    } else if exc.class().is(vm.ctx.exceptions.name_error) {
        let name = exc.as_object().get_attr("name", vm).unwrap();
        let mut tb = exc.traceback()?;
        for traceback in tb.iter() {
            tb = traceback;
        }

        let varnames = tb.frame.code.clone().co_varnames(vm);
        if let Some(suggestions) = calculate_suggestions(varnames.iter(), &name) {
            return Some(suggestions);
        };

        let globals: Vec<_> = tb.frame.globals.as_object().try_to_value(vm).ok()?;
        if let Some(suggestions) = calculate_suggestions(globals.iter(), &name) {
            return Some(suggestions);
        };

        let builtins: Vec<_> = tb.frame.builtins.as_object().try_to_value(vm).ok()?;
        calculate_suggestions(builtins.iter(), &name)
    } else {
        None
    }
}