You don't have to document it.. just abstract it.

Code:
$replacex(%format_string, [username], $+(_,%username,_), $!null, __)


or just make an alias for it:

Code:
alias isnull { return $iif($+(_,$1,_) == __, $true, $false) }


and inform them they should use $isnull([username])

- argv[0] on EFnet #mIRC
- "Life is a pointer to an integer without a cast"