$ juju run --unit namenode/0 'charms.reactive --help'
usage: charms.reactive [-h] [--format FMT | -r | -j | -p | -y | -c | -t]
                       {set_state,remove_state,get_states,is_state,all_states,any_states,any_hook,relation_call,hook,when,when_all,when_any,when_not,when_none,when_not_all,when_file_changed,only_once,mark_invoked,test,render_template}