This crate contains code to perform I/O operations from command line programs. This includes programs running in Fuchsia.
As a result, this code should be friendly to build and include using either the host toolchain or the fuchsia toolchain.
Ffx subtools should not use this crate directly, but rather use //src/developer/ffx/lib/writer which are host toolchain only, and include the code for dependency injection via TryFromEnv.