// *** before: ***
mod network;
use network::client; // a path from the crate root, unprefixed
use ::std::collections::HashMap; // an outside crate took a leading ::
// *** in version Rust 2018: ***
mod network;
use crate::network::client; // our own goes through crate::
use self::network::server; // a neighbour goes through self::
use std::collections::HashMap; // an outside one goes by the crate name