Add a method to retrieve the e-mail address of a user

Which is the simplest way of getting the email address of a wiki user? I know of:

Solution 1 (slower, but just one line):

$xwiki.getUserName($someUserName, "$email", false)

Solution 2 (faster, but 3 lines):

$userdoc = $xwiki.getDocument($someUserName)
$userdoc.use("XWiki.XWikiUsers")
$userdoc.getValue("email")

I'd preffer:

Solution 3 (faster and just one line):

$xwiki.getUserEmail($someUserName)