String.format("%08x", (System.currentTimeMillis() % 4294967295l))转python

Null refers to the concept of having no value or absence of data in a programming language or database. It is typically used to indicate that a variable or field is not assigned or does not have a value. In some programming languages, null is equivalent to false or zero, while in others, it is a distinct value that represents the absence of a value. In databases, null is used to represent missing or unknown data in a field.