def apply(self, docs, split=0, clear=True, parallelism=None, progress_bar=True):
        """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
        """
        super(CandidateExtractor, self).apply(
            docs,
            split=split,
            clear=clear,
            parallelism=parallelism,
            progress_bar=progress_bar,
        )
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