I'm reading Harry Potter for English study.
"Gryffindors have never gone so long without winning"
I think double negative means postive. So I think "Gryffindors have never gone so long without winning" means "Gryffindors have gone so long with winning".
But I heard that it means Gryffindors have been losing for a long time: their longest time ever.
Can you explain why???