Because of standard library's prelude, it's common for your libary to have its own prelude module as a starting point for
where users should import all of the most common data structures for using your library (e.g
It doesn't automatically get used in programs/libraries that use your crate, but it's a good convention to follow so people
know where to start.
Ferris says, "Be a good rustacean and help a fellow crab out with a good prelude!"