Request tutorial to work with Python!
I don't understand the `quick start` section with python on https://kaitai.io/

```
g = Gif.from_file("path/to/some.gif")

print "width = %d" % (g.logical_screen.image_width)
print "height = %d" % (g.logical_screen.image_height)
```

Does it mean:

1. `ksc -t python gif.ksy`
2. In python, just `import Gif`, then ..

But, what does `_io` mean? I need a whole quick start example. Thanks. :-D