Solution for Exercise 3.

Output is:

```bash
==> prep3: Info: Applying configuration version '1415392587'
==> prep3: Notice: Welcome to the Puppet for Hackers course!
==> prep3: Notice: /Stage[main]/P4h/Notify[welcome]/message: defined
'message' as 'Welcome to the Puppet for Hackers course!'
==> prep3: Notice: onepotatotwopotato
==> prep3: Notice: /Stage[main]/P4h::Prep3/Notify[potato]/message:
defined 'message' as 'onepotatotwopotato'
==> prep3: Notice: Hey mac
==> prep3: Notice: /Stage[main]/P4h::Prep3/Notify[hi]/message: defined
'message' as 'Hey mac'
==> prep3: Notice: Finished catalog run in 0.23 seconds
```