Using "and" in return
===

I'm taking Web Application Engineering course on Udacity. I noticed that the instructor use `and` operator in `return` statement in his validation method. And I didn't understand how it is possible to return 2 arguments. I think, it may be something like `if` statement. Could  anyone explain what it actually is? 

Here is the validation method:

    USER_RE = re.compile(r"^[a-zA-Z0-9_-]{3,20}$")
    def valid_username(username):
        return username and USER_RE.match(username)

Thanks in advance.