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: lib.rs
    path of file: ./repos/failure/failure_derive/src
    
    the code of the file until where you have to start completion: extern crate proc_macro2;
extern crate syn;

#[macro_use]
extern crate synstructure;
#[macro_use]
extern crate quote;

use proc_macro2::{TokenStream, Span};
use syn::LitStr;
use 
    
fn is_backtrace(bi: &&synstructure::BindingInfo) -> bool {
    match bi.ast().ty {
        syn::Type::Path(syn::TypePath {
            qself: None,
            path: syn::Path {
                segments: ref path, ..
            },
        }) => path.last().map_or(false, |s| {
            s.ident == "Backtrace" && s.arguments.is_empty()
        }),
        _ => false,
    }
}