handling case when answer is not a list

place_gen_evaluate.py

@@ -118,6 +118,8 @@ class Place_gen_evaluate(evaluate.Metric):
     
             try:
                 f_ans = ast.literal_eval(gen)
+                if not isinstance(f_ans, list):
+                    f_ans = [f_ans]
             except:
                 subs = ['[', ']', '(', ')', ' ']
                 pattern = r'(' + '|'.join(map(re.escape, subs)) + r')'