The flags from the previous recipe are a type of command-line argument. This chapter will expand on other uses for these arguments by constructing a command that supports nested subcommands. This will demonstrate Flagsets and also use positional arguments passed into your application.
Like the previous recipe, this one requires a main function to run. There are a number of third-party packages to deal with complex nested arguments and flags, but we'll investigate how to do that using only the standard library.
