128-bit binary value. It can be used as a more convenient container for
16-byte binary strings, which will be pretty printed as UUID or
IPv6 address.

=> UUID

Application is left responsible for UUID validation.

Simplest decoder can safely replace HEXLET's tag with 0x90 and decode it
as ordinary 16-byte binary string.

Example representations:

Nil UUID                             | 04 00000000000000000000000000000000
Max UUID                             | 04 FFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFF
0e875e3f-d385-49eb-87b4-be42d641c367 | 04 0E875E3FD38549EB87B4BE42D641C367
2001:db8::1234 IPv6                  | 04 20010db8000000000000000000001234