--- a/main_solution3/re.scala	Sat Mar 11 23:24:15 2023 +0000
+++ b/main_solution3/re.scala	Sat Sep 23 23:49:44 2023 +0100
@@ -62,7 +62,7 @@
   case SEQs(Nil) => ZERO
   case SEQs(r1::rs) => 
     if (nullable(r1)) ALT(SEQs(der(c, r1)::rs), der(c, SEQs(rs)))
-    else SEQs(der(c, r1):: rs)
+    else SEQs(der(c, r1) :: rs)
   case STAR(r1) => SEQ(der(c, r1), STAR(r1))
 }