Version flag alongside other commands

I have a script which has multiple commands, each of which have their own arguments etc. I would like to add a simple flag to be used standalone to simply display the version of my script. I would like the the `--help` display to additionally show users this flag is available without affecting the other commands. For instance if my script is called `foo`, I'd like to be able to do:

`foo --version` or `foo -v`

but I'd still like to do:

`foo mycommand myarg` etc.

The two closest solutions I've tried each have a downside:

- the flags and the commands are displayed in different help windows e.g. `foo --help` shows the help window for the flags whilst `foo` standlone shows the help window for the commands
- the help window shows both flags and commands but the flag is interpreted as a flag _to the commands_ such that if I type `foo --version`, the version is displayed but so is the help window because it thinks a command is missing

I'm using `fire==0.5.0`. Is there any way I can achieve this?