[improve] Allow symbol along with str and content in some places

src/process-args.typ

@@ -39,7 +39,7 @@
   if labels == none {  return () }
   let type = type(labels)
   if type == dictionary { labels = (labels,) } 
-  else if type in (content, str) { labels = ((content: labels),) } 
+  else if type in (symbol, content, str) { labels = ((content: labels),) } 
   else if type == dictionary { labels = ((content: labels),) } 
   let processed-labels = ()
   for label in labels {

src/quantum-circuit.typ

@@ -332,7 +332,7 @@
             dy: annotation.at("dy", default: 0pt),
             draw-params: draw-params
           )
-        } else if type(annotation) in (content, str) {
+        } else if type(annotation) in (symbol, content, str) {
           layer-below-circuit += place(annotation)
         } 
       }

src/verifications.typ

@@ -69,7 +69,7 @@
 
 #let verify-annotation-content(annotation-content) = {
   let content-type = type(annotation-content)
-  assert(content-type in (content, str, dictionary), message: "`annotate`: Unsupported callback return type `" + str(content-type) + "` (can be `dictionary` or `content`")
+  assert(content-type in (symbol, content, str, dictionary), message: "`annotate`: Unsupported callback return type `" + str(content-type) + "` (can be `dictionary` or `content`")
 
   if content-type == dictionary {
     assert("content" in annotation-content, message: "`annotate`: Missing field `content` in annotation. If the callback returns a dictionary, it must contain the key `content` and may specify coordinates with `dx` and `dy`.")