Update app.py

app.py

@@ -41,7 +41,7 @@ def predict(pilimg,Threshold):
     
     image_np = pil_image_as_numpy_array(pilimg)
     
-    if isnull(Threshold) or Threshold == 0:
+    if Threshold is None or Threshold == 0:
         Threshold=0.88
     # else:
     #     Threshold= float(Threshold)