diff --git a/utils/literal.py b/utils/literal.py
index ac41a93..c574306 100644
--- a/utils/literal.py
+++ b/utils/literal.py
@@ -21,6 +21,8 @@ class Literal:
 
     def __eq__(self, other):
         """Vergleicht den Wert mit einem anderen Wert."""
+        if other is None:
+            return False
         assert isinstance(other, Literal), "Can only compare with Literal or MemoryCell"
         self.compare_count += 1
         self.read_count += 1
@@ -29,6 +31,8 @@ class Literal:
 
     def __ne__(self, other):
         """Vergleicht den Wert der Speicherzelle mit einem anderen Wert."""
+        if other is None:
+            return True
         assert isinstance(other, Literal), "Can only compare with Literal or MemoryCell"
         self.compare_count += 1
         self.read_count += 1
diff --git a/vorlesung/01_grundlagen/euklid.py b/vorlesung/L01_grundlagen/euklid.py
similarity index 100%
rename from vorlesung/01_grundlagen/euklid.py
rename to vorlesung/L01_grundlagen/euklid.py
diff --git a/vorlesung/02_elementares_sortieren/bubble_game.py b/vorlesung/L02_elementares_sortieren/bubble_game.py
similarity index 100%
rename from vorlesung/02_elementares_sortieren/bubble_game.py
rename to vorlesung/L02_elementares_sortieren/bubble_game.py
diff --git a/vorlesung/02_elementares_sortieren/bubble_sorting.py b/vorlesung/L02_elementares_sortieren/bubble_sorting.py
similarity index 100%
rename from vorlesung/02_elementares_sortieren/bubble_sorting.py
rename to vorlesung/L02_elementares_sortieren/bubble_sorting.py
diff --git a/vorlesung/02_elementares_sortieren/insert_game.py b/vorlesung/L02_elementares_sortieren/insert_game.py
similarity index 100%
rename from vorlesung/02_elementares_sortieren/insert_game.py
rename to vorlesung/L02_elementares_sortieren/insert_game.py
diff --git a/vorlesung/02_elementares_sortieren/insert_sorting.py b/vorlesung/L02_elementares_sortieren/insert_sorting.py
similarity index 100%
rename from vorlesung/02_elementares_sortieren/insert_sorting.py
rename to vorlesung/L02_elementares_sortieren/insert_sorting.py
diff --git a/vorlesung/02_elementares_sortieren/select_game.py b/vorlesung/L02_elementares_sortieren/select_game.py
similarity index 100%
rename from vorlesung/02_elementares_sortieren/select_game.py
rename to vorlesung/L02_elementares_sortieren/select_game.py
diff --git a/vorlesung/02_elementares_sortieren/select_sorting.py b/vorlesung/L02_elementares_sortieren/select_sorting.py
similarity index 100%
rename from vorlesung/02_elementares_sortieren/select_sorting.py
rename to vorlesung/L02_elementares_sortieren/select_sorting.py
diff --git a/vorlesung/03_fortgeschrittenes_sortieren/heap_game.py b/vorlesung/L03_fortgeschrittenes_sortieren/heap_game.py
similarity index 100%
rename from vorlesung/03_fortgeschrittenes_sortieren/heap_game.py
rename to vorlesung/L03_fortgeschrittenes_sortieren/heap_game.py
diff --git a/vorlesung/03_fortgeschrittenes_sortieren/heap_sorting.py b/vorlesung/L03_fortgeschrittenes_sortieren/heap_sorting.py
similarity index 100%
rename from vorlesung/03_fortgeschrittenes_sortieren/heap_sorting.py
rename to vorlesung/L03_fortgeschrittenes_sortieren/heap_sorting.py
diff --git a/vorlesung/03_fortgeschrittenes_sortieren/quick_game.py b/vorlesung/L03_fortgeschrittenes_sortieren/quick_game.py
similarity index 100%
rename from vorlesung/03_fortgeschrittenes_sortieren/quick_game.py
rename to vorlesung/L03_fortgeschrittenes_sortieren/quick_game.py
diff --git a/vorlesung/03_fortgeschrittenes_sortieren/quick_sorting.py b/vorlesung/L03_fortgeschrittenes_sortieren/quick_sorting.py
similarity index 100%
rename from vorlesung/03_fortgeschrittenes_sortieren/quick_sorting.py
rename to vorlesung/L03_fortgeschrittenes_sortieren/quick_sorting.py
diff --git a/vorlesung/04_besondere_sortierverfahren/count_sorting.py b/vorlesung/L04_besondere_sortierverfahren/count_sorting.py
similarity index 100%
rename from vorlesung/04_besondere_sortierverfahren/count_sorting.py
rename to vorlesung/L04_besondere_sortierverfahren/count_sorting.py
diff --git a/vorlesung/L05_binaere_baeume/__init__.py b/vorlesung/L05_binaere_baeume/__init__.py
new file mode 100644
index 0000000..2dc50f9
--- /dev/null
+++ b/vorlesung/L05_binaere_baeume/__init__.py
@@ -0,0 +1 @@
+from vorlesung.L05_binaere_baeume.bin_tree import BinaryTree
diff --git a/vorlesung/05_binaere_baeume/bin_search.py b/vorlesung/L05_binaere_baeume/bin_search.py
similarity index 100%
rename from vorlesung/05_binaere_baeume/bin_search.py
rename to vorlesung/L05_binaere_baeume/bin_search.py
diff --git a/vorlesung/05_binaere_baeume/bin_tree.py b/vorlesung/L05_binaere_baeume/bin_tree.py
similarity index 98%
rename from vorlesung/05_binaere_baeume/bin_tree.py
rename to vorlesung/L05_binaere_baeume/bin_tree.py
index 7e6a4d3..a25c8f8 100644
--- a/vorlesung/05_binaere_baeume/bin_tree.py
+++ b/vorlesung/L05_binaere_baeume/bin_tree.py
@@ -1,4 +1,4 @@
-from bin_tree_node import BinaryTreeNode
+from vorlesung.L05_binaere_baeume.bin_tree_node import BinaryTreeNode
 from utils.project_dir import get_path
 from datetime import datetime
 
diff --git a/vorlesung/05_binaere_baeume/bin_tree_node.py b/vorlesung/L05_binaere_baeume/bin_tree_node.py
similarity index 100%
rename from vorlesung/05_binaere_baeume/bin_tree_node.py
rename to vorlesung/L05_binaere_baeume/bin_tree_node.py
diff --git a/vorlesung/__init__.py b/vorlesung/__init__.py
new file mode 100644
index 0000000..e69de29