one dude to writeln

[Arthur]

sub write()
var X=uo.getx()
var Y=uo.gety()
var Z=uo.getz()
var t = file("c:\test.txt")
t.open()
t.writeln(str(X)+","+str(Y)+","+str(Z))
t.close()
end sub

this only make one line with coordinates
how to add new line and write coordinates to this?