Style #12
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Constraints:

- The larger problem is decomposed into 'things' that make sense for
  the problem domain 

- Each 'thing' is a capsule of data that exposes one single procedure,
  namely the ability to receive and dispatch messages that are sent to
  it

- Message dispatch can result in sending the message to another capsule

Possible names:

- Letterbox
- Messaging style
- Objects
- Actors