This should also check and make sure it's a Gammavision file not an old maestro *.spe file which has a similar (but not compatible) syntax. This should raise an error. Something as simple as:
```python
if (line[0] == '$SPEC_ID:'):
    raise VersionError('This type of spe file is not supported')
```
should do the trick. If you need an old style .spe to test this let me know and I'll find one I can put in a gist.