correctly detecting build as a dir.

tree_structurer/cpp/tree_structurer.cpp

@@ -5,15 +5,16 @@
 namespace fs = std::filesystem;
 
 bool TreeStructurer::should_ignore_dir(const std::string& dirname) {
-    return dirname[0] == '.' || 
+    return dirname[0] == '.' ||
+           dirname[0] == '_'|| 
            dirname.find("build") != std::string::npos ||
            dirname == "venv" || 
-           dirname == "myenv";
+           dirname == "myenv" ||
+           dirname == "build";
 }
 
 bool TreeStructurer::should_ignore_file(const std::string& filename) {
-    return filename[0] == '.' || 
-           filename.find("build") != std::string::npos;
+    return filename[0] == '.';
 }
 
 std::string TreeStructurer::create_indent(int level) {