n.  The 'version' argument is optional; if given, the resulting
UUID will have its variant and version set according to RFC 4122,
overriding the given 'hex', 'bytes', 'bytes_le', 'fields', or 'int'.

is_safe is an enum exposed as an attribute on the instance.  It
indicates whether the UUID has been generated in a way that is safe
for multiprocessing applications, via uuid_generate_time_safe(3).
N