jgraichen/acfs — pull request #19 by nicolas-fricke (2014-02-13 14:04:29+00:00)
Title: Add new attribute type UUID

Check if given object looks like a UUID, eg:
`450b7a40-94ad-11e3-baa8-0800200c9a66`
Valid UUIDs are 16 byte numbers represented as
a hexadecimal string in five sub-groups seperated
by a dash. Each group has to consist of a fixed
number of hexadecimal digits:
| Group | Digits |
| -----:|:------ |
| 1 | 8 |
| 2 | 4 |
| 3 | 4 |
| 4 | 4 |
| 5 | 12 |

Read more about UUIDs:
[Wikipedia (en)](https://en.wikipedia.org/wiki/Universally_unique_identifier)