diff --git a/dlx.py b/dlx.py
--- a/dlx.py
+++ b/dlx.py
@@ -80,13 +80,14 @@ class Header(Column):
 			while c is not row:
 				c.col.cover()
 				c=c.right
-			self.search(k+1)
+			if self.search(k+1): return True
 			c=row.left
 			while c is not row:
 				c.col.uncover()
 				c=c.left
 			row=row.down
 		col.uncover()
+		return False
 
 	def chooseCol(self):
 		c=self.right
@@ -100,11 +101,14 @@ class Header(Column):
 		return res
 
 	def print(self):
+		res=[]
 		for r in self._res:
-			print(r.col.name,end=" ")
+			res.append([])
+			res[-1].append(r.col.name)
 			c=r.right
 			while c is not r:
-				print(c.col.name,end=" ")
+				res[-1].append(c.col.name)
 				c=c.right
-			print()
-		print()
+			res[-1].sort(key=str)
+		for line in res:
+			print(line)