code: def update(self, docs=None, split=0, parallelism=None, progress_bar=True):
          
          self.apply(
              docs=docs,
              split=split,
              train=True,
              clear=False,
              parallelism=parallelism,
              progress_bar=progress_bar,
          )
docs: Update the features of the specified candidates.
  
          :param docs: If provided, apply features to all the candidates in these
              documents.
          :param split: If docs is None, apply features to the candidates in this
              particular split.
          :type split: int
          :param parallelism: How many threads to use for extraction. This will
              override the parallelism value used to initialize the Featurizer if
              it is provided.
          :type parallelism: int
          :param progress_bar: Whether or not to display a progress bar. The
              progress bar is measured per document.
          :type progress_bar: bool