I'm having issues using TAB for indentation when viewing a Snakefile in emacs with snakemake-mode.

When I open a Snakefile in emacs, the syntax highlighting looks correct, but if try to use TAB for indentation, the cursor stays in column 0 and instead I get the error :
`Symbol's function definition is void: looking-at-p`

Followed directions here:
http://melpa.org/#/snakemake-mode

My setup:
* GNU Emacs 22.1.1 
* snakemake-mode commit SHA 295bbfbc94727691d7e9919abf9f358ab7a6b241
* file snakemake-mode.el in my ~/.emacs.d 
* In my ~/.emacs :
```
(add-to-list 'load-path "~/.emacs.d/")
(require 'snakemake-mode)
```
* Also tried in my ~/.emacs :
```
(load-file "~/.emacs.d/snakemake-mode.el")
```


Next I'll try installing from MELPA but i thought this should be documented somewhere. Of course, any insight appreciated. 

---
Reply to this email directly or view it on GitHub:
https://github.com/kyleam/snakemake-mode/issues/4