Retrogress is a wrapper around indicatif, providing structs and traits that have a simple and limited API and that can be passed between modules and functions.
For advanced progress bar usage, in a project that does not need to share a progress bar between different sections of code, one may be better served by directly using indicatif (or any other of the many wonderful crates available). This crate can be used to construct progress bars that can be passed around, borrowed, or moved between threads.
cargo run --example sync