Use contains function, since the content may have multiple characters

matching.go

@@ -47,7 +47,7 @@ func findAllMatchesHelper(start *State, str string, indices []matchIndex, offset
 	startingFrom := i               // Store starting index
 	// Increment until we hit a character matching the start state (assuming not 0-state)
 	if start.isEmpty == false {
-		for i < len(str) && int(str[i]) != start.content {
+		for i < len(str) && !start.content.contains(int(str[i])) {
 			i++
 		}
 		startIdx = i