When the user enters an invalid subcommand
usage: nova [--username USERNAME] [--apikey APIKEY] [--projectid PROJECTID]
[--url URL] [--version VERSION]
<subcommand> ...
nova: error: argument <subcommand>: invalid choice: 'f' (choose from 'rename', 'zone-add', 'suspend', 'help', 'show', 'migrate', 'zone-delete', 'actions', 'meta', 'add-fixed-ip', 'image-list', 'pause', 'zone', 'flavor-list', 'boot', 'reboot', 'remove-fixed-ip', 'image-meta', 'image-delete', 'unpause', 'root-password', 'rescue', 'resume', 'image-show', 'zone-info', 'resize-revert', 'resize-confirm', 'resize', 'image-create', 'list', 'unrescue', 'zone-list', 'diagnostics', 'zone-boot', 'rebuild', 'delete')
we let the user know to run **nova help** to get a list of commands?
Finished with the code. Will send a review when confirmed.