Style #21
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Constraints:

- Every single procedure and function checks the sanity of its
  arguments and either returns something sensible when the arguments
  are unreasonable or assigns them reasonable values

- All code blocks check for possible errors and escape the block
  when things go wrong, setting the state to something reasonable

Possible names:

- Constructive
- Defensive
- Hopeful
- Shit happens, life goes on

(See http://en.wikipedia.org/wiki/Constructivism_(mathematics))