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/objc2/crates/objc2-proc-macros/src
    
    the code of the file until where you have to start completion: //! Procedural macros for the [`objc2` project](https://github.com/madsmtm/objc2).
//!
//! You should not need to use this crate directly, all its public items are
//! exported in other crates.

#![warn(elided_lifetimes_in_paths)]
#![warn(missing_docs)]
#![warn(missing_copy_implementations)]
#![warn(missing_debug_implementations)]
#![deny(non_ascii_idents)]
#![warn(unreachable_pub)]
#![deny(unsafe_op_in_unsafe_fn)]
#![warn(clippy::cargo)]
#![warn(clippy::ptr_as_ptr)]
#![warn(clippy::missing_errors_doc)]
#![warn(clippy::missing_panics_doc)]
// Update in Cargo.toml as well.
#![doc(html_root_
    
pub fn __hash_idents(input: TokenStream) -> TokenStream {
    // Create the hasher
    let mut hasher = std::collections::hash_map::DefaultHasher::new();

    // Hash each ident
    for ident in get_idents(input) {
        ident.to_string().hash(&mut hasher);

        // Hash the source code location of the ident
        //
        // HACK: the only somewhat-reasonable way to get "unique" data in a
        // proc macro right now is from the `Debug` formatter for spans which
        // includes the source code location... so just hash the whole `Debug`
        // format output of the span
        //
        // Prior art in the `defmt` crate, see here:
        // https://github.com/knurling-rs/defmt/blob/defmt-v0.3.1/macros/src/construct.rs
        format!("{:?}", ident.span()).hash(&mut hasher);
    }

    // Get the hash from the hasher and return it as 16 hexadecimal characters
    let s = format!("{:016x}", hasher.finish());
    TokenTree::Literal(Literal::string(&s)).into()
}