Update app.py

app.py

@@ -103,9 +103,9 @@ def load_recommender(paths, start_page=1):
     return 'Corpus Loaded.'
 
 
-def generate_text(prompt, engine=os.environ('Engine')):
+def generate_text(prompt):
     completions = openai.Completion.create(
-        engine=engine,
+        engine=os.environ('Engine'),
         prompt=prompt,
         max_tokens=512,
         n=1,