mix ussd.lint
mix ussd.lint MyApp.Ussd.States.Welcome
mix ussd.lint --strictWith no arguments, discovers every compiled module under config :ussd, :namespace
that flags itself initial: true (see use Ussd.State) and walks from there. Pass
one or more state modules explicitly to lint a specific flow (or one whose entry
points aren't flagged initial).
--strict makes warnings (not just errors) fail the command.