--- a/main_solution3/re.scala	Sat Dec 17 12:42:49 2022 +0000
+++ b/main_solution3/re.scala	Fri Dec 23 16:52:34 2022 +0000
@@ -93,7 +93,7 @@
 
 def SEQs_smart(rs: List[Rexp]) : Rexp = rs match {
   case Nil => ONE
-  case ZERO::nil => ZERO
+  case ZERO::Nil => ZERO
   case r::Nil => r
   case rs => SEQs(rs) 
 }
@@ -198,4 +198,4 @@
 // if nullable(r1)  
   ALTs(SEQs(der(c, r1)::rs)::(rs filter what is nullable) .map(der(c,_)))
 
-*/
\ No newline at end of file
+*/