once again is not -> != ; weird python versioning error causing this?

model.py

@@ -87,7 +87,7 @@ class VirTexModel:
             )
             subreddit_tokens = torch.tensor(subreddit_tokens, device=self.device).long()
 
-        if prompt is not "":
+        if prompt != "":
             # at present prompts without subreddits will break without this change
             # TODO FIX
             cap_tokens = self.tokenizer.encode(prompt)
@@ -129,7 +129,7 @@ class VirTexModel:
                 subreddit, rest_of_caption = "", caption.strip()
 
             # split prompt for coloring:
-            if prompt is not "":
+            if prompt != "":
                 _, rest_of_caption = caption.split(prompt.strip())
 
             is_valid_subreddit = subreddit in self.valid_subs