unsigned result = 1;
for (unsigned i = 2; i < n; i++) {
    result *= i;
}

config
        .endpoints
        .iter()
        .map(|next_endpoints| craft_for_endpoints_pair(&payload, next_endpoints, config.ip_ttl))
        .collect()

let mut result = Vec::with_capacity(config.endpoints.len());

    for next_endpoints in &config.endpoints {
        let mut datagrams = Vec::with_capacity(payload.len());
        for payload_portion in &payload {
            datagrams.push(packets::ip_udp_packet(
                next_endpoints,
                payload_portion,
                config.ip_ttl,
            ));
        }

        result.push(datagrams.into_iter());