Open Safari in private browsing

#!/usr/bin/osascript

set safariRunning to true
if application "Safari" is not running then
    set safariRunning to false
end if

tell application "Safari"
    if safariRunning = false then
        delay 0.1
        tell application "Safari" to close window 1
    end if

    make new document
    activate

    tell application "System Events"
        keystroke "W" using {command down}
        keystroke "N" using {shift down, command down}
    end tell
end tell