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: proposal.rs
    path of file: ./repos/snarkOS/node/bft/src/helpers
    
    the code of the file until where you have to start completion: // Copyright (C) 2019-2023 Aleo Systems Inc.
// This file is part of the snarkOS library.

// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at:
// http://www.apache.org/licenses
    
    pub fn nonsigners(&self, committee: &Committee<N>) -> HashSet<Address<N>> {
        // Retrieve the current signers.
        let signers = self.signers();
        // Initialize a set for the non-signers.
        let mut nonsigners = HashSet::new();
        // Iterate through the committee members.
        for address in committee.members().keys() {
            // Insert the address if it is not a signer.
            if !signers.contains(address) {
                nonsigners.insert(*address);
            }
        }
        // Return the non-signers.
        nonsigners
    }