code: def apply(self, docs, split=0, clear=True, parallelism=None, progress_bar=True):
          
          super(CandidateExtractor, self).apply(
              docs,
              split=split,
              clear=clear,
              parallelism=parallelism,
              progress_bar=progress_bar,
          )
docs: Run the CandidateExtractor.
  
          :Example: To extract candidates from a set of training documents using
              4 cores::
  
                  candidate_extractor.apply(train_docs, split=0, parallelism=4)
  
          :param docs: Set of documents to extract from.
          :param split: Which split to assign the extracted Candidates to.
          :type split: int
          :param clear: Whether or not to clear the existing Candidates
              beforehand.
          :type clear: bool
          :param parallelism: How many threads to use for extraction. This will
              override the parallelism value used to initialize the
              CandidateExtractor 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