Chex is a lightweight Node.js library that wraps Execa to let you “chex‑out” command‑line tools before using them. It verifies that a given executable is present and, if a semver range is supplied, ensures the tool’s version satisfies that range, then returns an Execa‑compatible wrapper (with async and sync methods) for running the command. It’s aimed at developers building CLIs or automation scripts that depend on external binaries.