Hide helper function in closure

linguistic-abbreviations.typ

@@ -113,17 +113,14 @@
 
 #let fmnt = smallcaps([fmnt])
 
-
-//Appendix: List of Standard Abbreviations
-
-#let mark_used(symbol) = {
+#let emit_abbreviation(symbol) = {
+  let mark_used(symbol) = {
     used_abbreviations.update(cur => {
       cur.insert(symbol, true)
       cur
     })
-}
+  }
 
-#let emit_abbreviation(symbol) = {
   mark_used(symbol)
   smallcaps(lower(symbol))
 }