Create a new Universal Unique Identifier (UUID) and print it to standard output. The generated UUID consists of five hyphen-separated groups of hex digits (e.g., 3cdfc61d-87d3-41b5-ba50-32870b33dc67). The default is to generate a random-based UUID, but this requires that a high-quality random-number generator be available on the system.
Generate a random-based UUID.
Generate a time-based UUID.