Creates and returns an RFC4122 version 4 compliant UUID.
The string is in the form: xxxxxxxx-xxxx-4xxx-yxxx-xxxxxxxxxxxx where each x is replaced with a random
hexadecimal digit from 0 to f, and y is replaced with a random hexadecimal digit from 8 to b.
Creates and returns an RFC4122 version 4 compliant UUID.
The string is in the form:
xxxxxxxx-xxxx-4xxx-yxxx-xxxxxxxxxxxxwhere eachxis replaced with a random hexadecimal digit from 0 to f, andyis replaced with a random hexadecimal digit from 8 to b.