## Identifiers

Fatcat entity identifiers are 128-bit UUIDs encoded in base32 format. Revision
ids are also UUIDs, and encoded in normal UUID fashion, to disambiguate from
edity identifiers.

Python helpers for conversion:

    import base64
    import uuid

    def fcid2uuid(s):
        s = s.split('_')[-1].upper().encode('utf-8')
        assert len(s) == 26
        raw = base64.b32decode(s + b"======")
        return str(uuid.UUID(bytes=raw)).lower()

    def uuid2fcid(s):
        raw = uuid.UUID(s).bytes
        return base64.b32encode(raw)[:26].lower().decode('utf-8')

    test_uuid = '00000000-0000-0000-3333-000000000001'
    assert test_uuid == fcid2uuid(uuid2fcid(test_uuid))