To 'unload' a snippet, three things have to be done:
1. Destroy all the instances that were created by the snippet.
This is done by calling `iii.destroy();` for each instance
iii. Note that if you have created references to the instance
outside of the snippet, you must `delete` those references.
2. Destroy all classes that were created by the snippet. This
is done by calling `ccc.destroy();` for each class ccc. Note
that if you have created references to the class outside of
the snippet, you must `delete` those references.
3. Unload the snippet. This is done by calling
`sss.unload()`, where sss is the name of the snippet (in the
import tag).
At this point, you can re-load the snippet by calling
`sss.load()`. If you know you will never use the snippet
again, you can call `sss.destroy();` to remove the snippet
from your application altogether.