diff -r 44f7b76d1106 -r b619d80f61fa src/Pure/ROOT.scala
--- a/src/Pure/ROOT.scala	Sat Mar 11 13:37:58 2023 +0100
+++ b/src/Pure/ROOT.scala	Sat Mar 11 14:18:56 2023 +0100
@@ -25,4 +25,5 @@
   val proper_string = Library.proper_string _
   def proper_list[A](list: List[A]): Option[List[A]] = Library.proper_list(list)
   def if_proper[A](x: Iterable[A], body: => String): String = Library.if_proper(x, body)
+  def if_proper(b: Boolean, body: => String): String = Library.if_proper(b, body)
 }