#compdef choose_tmux
 
 _choose_tmux() {
   local curcontext="$curcontext" state line
   typeset -A opt_args
 
   _arguments '1: :->session'
 
   case $state in
     session)
       for session in $(tmux list-sessions -F '#{session_name}'); do
         compadd "$@" $session
       done
       ;;
   esac
 }