diff --git a/.gitignore b/.gitignore
index eac483a..0e5ac79 100644
--- a/.gitignore
+++ b/.gitignore
@@ -1,2 +1,2 @@
 .venv
-**/__pycache__
\ No newline at end of file
+__pycache__
\ No newline at end of file
diff --git a/Tagger.py b/Tagger.py
index c08322a..c093cf1 100644
--- a/Tagger.py
+++ b/Tagger.py
@@ -1,6 +1,11 @@
+# Imports
 import tkinter as tk
 from tkinter import ttk
 
 from src.gui.gui import main
+from src.core.file_handler import list_files
 
-main()
\ No newline at end of file
+# Functions
+main()
+a = list_files("./src/core")
+print(a)
\ No newline at end of file
diff --git a/src/core/file_handler.py b/src/core/file_handler.py
index e69de29..f3677fd 100644
--- a/src/core/file_handler.py
+++ b/src/core/file_handler.py
@@ -0,0 +1,22 @@
+# Module header
+import sys
+
+if __name__ == "__main__":
+    sys.exit("This module is not intended to be executed as the main program.")
+
+# Imports
+from pathlib import Path
+
+# Functions
+def list_files(folder_path: str | Path) -> list[Path]:
+    """
+    Vrátí seznam Path objektů všech souborů uvnitř složky (rekurzivně).
+
+    :param folder_path: cesta ke složce (string nebo Path)
+    :return: list objektů Path
+    """
+    folder = Path(folder_path)
+    if not folder.is_dir():
+        raise NotADirectoryError(f"{folder} není platná složka.")
+
+    return [file_path for file_path in folder.rglob("*") if file_path.is_file()]
\ No newline at end of file
diff --git a/src/core/image_handler.py b/src/core/image_handler.py
index 132e449..d801316 100644
--- a/src/core/image_handler.py
+++ b/src/core/image_handler.py
@@ -1,6 +1,14 @@
+# Module header
+import sys
+
+if __name__ == "__main__":
+    sys.exit("This module is not intended to be executed as the main program.")
+
+# Imports
 from PIL import Image, ImageTk
 
-def load_icon(path):
+# Functions
+def load_icon(path) -> ImageTk.PhotoImage:
     img = Image.open(path)
     img = img.resize((16, 16), Image.Resampling.LANCZOS)
     return ImageTk.PhotoImage(img)
\ No newline at end of file
diff --git a/src/gui/gui.py b/src/gui/gui.py
index 4fb73f0..23dce52 100644
--- a/src/gui/gui.py
+++ b/src/gui/gui.py
@@ -1,8 +1,16 @@
+# Module header
+import sys
+
+if __name__ == "__main__":
+    sys.exit("This module is not intended to be executed as the main program.")
+
+# Imports
 import tkinter as tk
 from tkinter import ttk
 from src.core.image_handler import load_icon
 
-def main():
+# Functions
+def main() -> None:
     root = tk.Tk()
     root.title("Ukázka rozložení")
     root.geometry("800x600")
@@ -37,7 +45,7 @@ def main():
     states = {}
 
     # Funkce pro přepnutí checkboxu
-    def toggle(event):
+    def toggle(event) -> None:
         region = tree.identify("region", event.x, event.y)
         if region == "tree":
             item_id = tree.identify_row(event.y)
@@ -99,7 +107,4 @@ def main():
     tree.bind("<Button-3>", tree_right_click)
     listbox.bind("<Button-3>", list_right_click)
 
-    root.mainloop()
-
-if __name__ == "__main__":
-    main()
\ No newline at end of file
+    root.mainloop()
\ No newline at end of file