diff --git a/src/tree.py b/src/tree.py
index e64094557022fcce0891ee680c4850284715e8f4..b8cfb5f8ae0913e84c9e5581359a7619f4b93369 100644
--- a/src/tree.py
+++ b/src/tree.py
@@ -15,8 +15,9 @@ formatter = logging.Formatter('%(asctime)s - %(levelname)s - %(message)s')
 handler.setFormatter(formatter)
 logger.addHandler(handler)
 
+
 def load_json(p):
-    with open(p, 'r') as f:
+    with open(p, 'r', encoding='utf-8') as f:
         return json.loads(f.read())
 
 
@@ -100,11 +101,13 @@ class TreeWalker:
             for index, chapter in enumerate(level_node["children"]):
                 chapter_title = list(chapter.keys())[0]
                 chapter_node = list(chapter.values())[0]
-                chapter_path = os.path.join(level_path, f"{index+1}.{chapter_title}")
+                chapter_path = os.path.join(
+                    level_path, f"{index+1}.{chapter_title}")
                 self.load_sections(chapter_path, chapter_node)
                 for index, section_node in enumerate(chapter_node["children"]):
                     section_title = list(section_node.keys())[0]
-                    full_path = os.path.join(chapter_path, f"{index}.{section_title}")
+                    full_path = os.path.join(
+                        chapter_path, f"{index}.{section_title}")
                     if os.path.isdir(full_path):
                         self.ensure_exercises(full_path)
 
@@ -230,8 +233,8 @@ class TreeWalker:
             config = {
                 "node_id": self.gen_node_id(),
                 "keywords": [],
-                "children":[],
-                "export":[]
+                "children": [],
+                "export": []
             }
             dump_json(config_path, config, exist_ok=True, override=True)
         else:
@@ -295,4 +298,3 @@ class TreeWalker:
             if "exercise_id" not in exercise:
                 exercise["exercise_id"] = uuid.uuid4().hex
                 dump_json(full_name, exercise)
-