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: sigverify.rs
    path of file: ./repos/hypercube/src
    
    the code of the file until where you have to start completion: use counter::Counter;
use log::Level;
use packet::{Packet, SharedPackets};
use std::mem::size_of;
use std::sync::atomic::AtomicUsize;
use transaction::{PUB_KEY_OFFSET, SIGNED_DATA_OFFS
    
    fn test_verify_n(n: usize, modify_data: bool) {
        let tx = test_tx();
        let mut packet = make_packet_from_transaction(tx);

        // jumble some data to test failure
        if modify_data {
            packet.data[20] = packet.data[20].wrapping_add(10);
        }

        // generate packet vector
        let batches: Vec<_> = (0..2)
            .map(|_| {
                let packets = SharedPackets::default();
                packets
                    .write()
                    .unwrap()
                    .packets
                    .resize(0, Default::default());
                for _ in 0..n {
                    packets.write().unwrap().packets.push(packet.clone());
                }
                assert_eq!(packets.read().unwrap().packets.len(), n);
                packets
            }).collect();
        assert_eq!(batches.len(), 2);

        // verify packets
        let ans = sigverify::ed25519_verify(&batches);

        // check result
        let ref_ans = if modify_data { 0u8 } else { 1u8 };
        assert_eq!(ans, vec![vec![ref_ans; n], vec![ref_ans; n]]);
    }