encoding/HEXLET

    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