Refactor switch statements

scripts/Windows/OS/User/Add.ps1

@@ -25,7 +25,7 @@ function New-PersonalUser([Context] $context, [string] $userName)
     }
 
     switch (Get-UserStage) {
-        { $_ -in $null,$creationStage } {
+        { (-not $_) -or ($_ -eq $creationStage) } {
             Set-UserStage $creationStage;
 
             if (-not (Get-LocalUser $userName -ErrorAction SilentlyContinue)) {