diff --git a/.python-version b/.python-version
new file mode 100644
index 0000000..24ee5b1
--- /dev/null
+++ b/.python-version
@@ -0,0 +1 @@
+3.13
diff --git a/ToDo.md b/ToDo.md
new file mode 100644
index 0000000..492bda1
--- /dev/null
+++ b/ToDo.md
@@ -0,0 +1,5 @@
+# ToDo list
+
+- proper folder names and file names and location of methods
+- stub files .pyi
+- fix all remaning check errors
diff --git a/pyproject.toml b/pyproject.toml
index 17be3b7..427a272 100644
--- a/pyproject.toml
+++ b/pyproject.toml
@@ -24,7 +24,7 @@ explicit = true
 requires = ["hatchling"]
 build-backend = "hatchling.build"
 
-# MARK: Python tools
+# MARK: Python linting
 [tool.pyright]
 typeCheckingMode = "strict"
 reportMissingImports = "information"
diff --git a/src/CoreLibs/py.typed b/src/CoreLibs/py.typed
new file mode 100644
index 0000000..e69de29