Fix isa plot

attention_app/isa.py

@@ -9,6 +9,11 @@ try:
 except LookupError:
     nltk.download('punkt')
 
+try:
+    nltk.data.find('tokenizers/punkt_tab')
+except LookupError:
+    nltk.download('punkt_tab')
+
 def get_sentence_boundaries(text: str, tokens: List[str], tokenizer, inputs) -> Tuple[List[str], List[int]]:
     """
     Split text into sentences and map tokens to sentences.