code: def replace_variables(sentence: List[str],
                        sentence_variables: Dict[str, str]) -> Tuple[List[str], List[str]]:
      
      tokens = []
      tags = []
      for token in sentence:
          if token not in sentence_variables:
              tokens.append(token)
              tags.append("O")
          else:
              for word in sentence_variables[token].split():
                  tokens.append(word)
                  tags.append(token)
      return tokens, tags
docs: Replaces abstract variables in text with their concrete counterparts.