Rudimentary zsh completion for odeke-em/drive (a Google Drive utility)

_drive

#compdef drive drive-google
local cmnd desc

if [[ $CURRENT == 2 ]]
then
   local -a options
   drive |
      grep '^  [a-z]' |
      while read cmnd desc
      do
         options+=( "$cmnd""[$desc]" )
      done
   _values 'commands' $options

elif (( 2 < $CURRENT ))
then
   # Argument completion.
   local -a options
   drive $words[2] -h 2>&1 1> /dev/null |
      grep '^  -[a-z]' |
      sed 's/: / /; s/=""/=/' |
      while read cmnd desc
      do
         options+=( "$cmnd""[$desc]" )
      done
   if (( 0 < $#options ))
   then
      _values 'options' $options
   fi

   # File/directory completion.
   case $words[2] in
      # These don't take file arguments.
      'about'      ) true ;;
      'deinit'     ) true ;;
      'emptytrash' ) true ;;
      'features'   ) true ;;
      'help'       ) true ;;
      'init'       ) true ;;
      'quota'      ) true ;;
      'version'    ) true ;;

      # Everything else does (I think).
      * ) _path_files -f ;;
   esac
fi

how can i use it?