A regular plugin only needs to have execution priviledges.
For instance, lets look at this 'hello world' plugin:

```bash
#!/bin/bash
echo "hello world!"
```

If 'hello world' takes a lot of time, we might want to cache the result.
Results are cached for `status-interval` seoconds. lets look at the following plugin:

```bash
#!/bin/bash
PLUGIN_DIR=$(tmux show-option -gqv "@status_variables_dir")
source "$PLUGIN_DIR/utils/sdk.sh"

on_cache_miss() {
   echo "hello world!"
   sleep 1
}

echo "$(get_cached_value on_cache_miss)"
```

`on_cache_miss` will run only when `status-interval` seconds have passed.
This is important because tmux might refreshe the status line when redrawing the pane.
Every time you press <Enter> or create a new pane, the status line is refreshed which causes many script calls.

Now all that's left is to run it:
1. Dump the content of the script to the `scripts_directory`, and name it `hello_world.tmux`
2. Add `set -g status-left "#{hello_world}"` to your `tmux.conf` and your good to go!