diff --git a/manimlib/utils/debug.py b/manimlib/utils/debug.py
index f877af8b..9270c276 100644
--- a/manimlib/utils/debug.py
+++ b/manimlib/utils/debug.py
@@ -24,7 +24,7 @@ def print_family(mobject: Mobject, n_tabs: int = 0) -> None:
 
 
 def index_labels(
-    mobject: Mobject | np.ndarray, 
+    mobject: Mobject, 
     label_height: float = 0.15
 ) -> VGroup:
     labels = VGroup()
@@ -35,9 +35,3 @@ def index_labels(
         label.set_stroke(BLACK, 5, background=True)
         labels.add(label)
     return labels
-
-
-def get_runtime(func: Callable) -> float:
-    now = time.time()
-    func()
-    return time.time() - now