add download button

app.py

@@ -80,7 +80,7 @@ def molecule(input_pdb):
         </body></html>"""
     )
 
-    return dw_script + f"""<iframe style="width: 100%; height: 600px" name="result" allow="midi; geolocation; microphone; camera; 
+    return f"""<iframe style="width: 100%; height: 600px" name="result" allow="midi; geolocation; microphone; camera; 
     display-capture; encrypted-media;" sandbox="allow-modals allow-forms 
     allow-scripts allow-same-origin allow-popups 
     allow-top-navigation-by-user-activation allow-downloads" allowfullscreen=""