entferneBlaetter :: NBaum a -> NBaum a
entferneBlaetter (NKnoten s xs) = NKnoten s [entferneBlaetter x | x <- xs, not $ isLeaf x]
entferneBlaetter :: NBaum a -> NBaum a
entferneBlaetter (NKnoten s xs) = NKnoten s [entferneBlaetter x | x <- xs, not $ isLeaf x]
entferneBlaetter (NKnoten s xs) = NKnoten s [entferneBlaetter x | x <- xs, not $ isLeaf x]