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: util.rs
    path of file: ./repos/phaser/phaser/vendor/wasm-bindgen-backend/src
    
    the code of the file until where you have to start completion: //! Common utility function for manipulating syn types and
//! handling parsed values

use std::collections::hash_map::DefaultHasher;
use std::env;
use std::fmt;
use std::hash::{Hash, Hasher};
use std::iter::FromIterator;
use std::sync::atomic::AtomicBool;
use std::sync::atomic::AtomicUsize;
use std::sync::atomic::Ordering::SeqCst;

use crate::ast;
use proc_macro2::{self, Ident};
use syn;

/// Check whether a given `&str` is a Rust keyword
fn is_rust_keyword(name: &str) -> bool {
    match name {
        "abstract" | "alignof" | "as" | "become" | "box" | "break" | "const" | "continue"
        | "crate" | "do" | "else" | "enum" | "extern" | "false" | "final" | "fn" | "for" | "if"
        | "impl" | "in" | "let" | "loop" | "macro" | "match" | "mod" | "move" | "mut"
        | "offsetof" | "override" | "priv" | "proc" | "pub" | "pure" | "ref" | "return"
        | "Self" | "self" | "sizeof" | "static" | "struct" | "super" | "trait" | "true"
        | "type" | "typeof" | "unsafe" | "unsized" | "use" | "virtual" | "where" | "while"
        | "yield" | "bool" | "_" => tr
    
pub fn rust_ident(name: &str) -> Ident {
    if name == "" {
        panic!("tried to create empty Ident (from \"\")");
    } else if is_rust_keyword(name) {
        Ident::new(&format!("{}_", name), proc_macro2::Span::call_site())

    // we didn't historically have `async` in the `is_rust_keyword` list above,
    // so for backwards compatibility reasons we need to generate an `async`
    // identifier as well, but we'll be sure to use a raw identifier to ease
    // compatibility with the 2018 edition.
    //
    // Note, though, that `proc-macro` doesn't support a normal way to create a
    // raw identifier. To get around that we do some wonky parsing to
    // roundaboutly create one.
    } else if name == "async" {
        let ident = "r#async"
            .parse::<proc_macro2::TokenStream>()
            .unwrap()
            .into_iter()
            .next()
            .unwrap();
        match ident {
            proc_macro2::TokenTree::Ident(i) => i,
            _ => unreachable!(),
        }
    } else if name.chars().next().unwrap().is_ascii_digit() {
        Ident::new(&format!("N{}", name), proc_macro2::Span::call_site())
    } else {
        raw_ident(name)
    }
}