from_string ---------> fromstring (-_-)

app.py

@@ -45,7 +45,7 @@ def paper_finder(topics:list, max_paper:int)-> str: #it's import to specify the
             response.raise_for_status()
             
             # parsing element tree as text
-            root = ET.from_string(response.text)
+            root = ET.fromstring(response.text)
 
             # extract paper information
             papers = []