diff --git a/src/models/category.py b/src/models/category.py
index 4c64c1b..c296834 100644
--- a/src/models/category.py
+++ b/src/models/category.py
@@ -77,8 +77,12 @@ class Category(ExportBaseModel):
         return f'Category.from_str("{self.__str__()}")'
 
     def get_budget(self, date_valid: date | None) -> float:
+        # TODO
         ...
 
+    def get_tree_to_root(self) -> CategoryTree:
+        # TODO (maybe)
+        ...
 
 class CategoryDb(BaseModelDb):
     __tablename__ = "category"
@@ -256,6 +260,9 @@ class CategoryTree(BaseModel):
             result += sum(category.category.get_budget(date_valid) for category in self.sub_categories)
         return result
 
+    def __add__(self, other):
+        ...
+
 def build_category_tree(transactions: list[Transaction]) -> list[CategoryTree]:
     # TODO: loop through flat list a build a category tree
     result = []