make it shorter

CommonData/column.cpp

@@ -988,7 +988,7 @@ stringvec Column::nonFilteredLevels()
 
         // Use the right label order
         for (std::string& label : _labelsTemp)
-            if (levels.find(label) != levels.end())
+            if (levels.count(label))
                 _nonFilteredLevels.push_back(label);
     }