diff --git a/src/superintendent/acquisition_functions/functions.py b/src/superintendent/acquisition_functions/functions.py
index e209660..f8ab548 100644
--- a/src/superintendent/acquisition_functions/functions.py
+++ b/src/superintendent/acquisition_functions/functions.py
@@ -58,11 +58,10 @@ def margin(probabilities: np.ndarray) -> np.ndarray:
         new labels and catching any minority classes the algorithm currently
         classifies as a different label.
     """
-    margin = (
+    return (
         np.sort(probabilities, axis=1)[:, -1]
         - np.sort(probabilities, axis=1)[:, -2]
     )
-    return margin
 
 
 @make_acquisition_function(handle_multioutput="mean")  # noqa: D002
@@ -86,8 +85,7 @@ def certainty(probabilities: np.ndarray):
         classifies as a different label.
 
     """
-    certainty = probabilities.max(axis=-1)
-    return certainty
+    return probabilities.max(axis=-1)
 
 
 @make_acquisition_function(handle_multioutput="mean")
diff --git a/src/superintendent/base.py b/src/superintendent/base.py
index 8134c8e..eb82d83 100644
--- a/src/superintendent/base.py
+++ b/src/superintendent/base.py
@@ -189,9 +189,7 @@ def _annotation_iterator(self):
             self._display(x)
             y = yield
 
-            if y is None:
-                pass
-            else:
+            if y is not None:
                 self.queue.submit(id_, y)
 
             self.progressbar.value = self.queue.progress
@@ -285,13 +283,13 @@ def _compose(self):
         ]
 
     def _render_processing(self, message="Rendering..."):
-        message = (
-            "<h1>{}".format(message)
-            + '<i class="fa fa-spinner fa-spin"'
-            + ' aria-hidden="true"></i>'
-        )
-        processing_display = widgets.HTML(value=message)
         with self.feature_output:
+            message = (
+                "<h1>{}".format(message)
+                + '<i class="fa fa-spinner fa-spin"'
+                + ' aria-hidden="true"></i>'
+            )
+            processing_display = widgets.HTML(value=message)
             IPython.display.clear_output()
             display.default_display_function(processing_display)