def apply(self, docs, clear=True, parallelism=None, progress_bar=True):
super(MentionExtractor, self).apply(<EOL>docs, clear=clear, parallelism=parallelism, progress_bar=progress_bar<EOL>)<EOL>
Run the MentionExtractor.

        :Example: To extract mentions from a set of training documents using
            4 cores::

                mention_extractor.apply(train_docs, parallelism=4)

        :param docs: Set of documents to extract from.
        :param clear: Whether or not to clear the existing Mentions
            beforehand.
        :type clear: bool
        :param parallelism: How many threads to use for extraction. This will
            override the parallelism value used to initialize the
            MentionExtractor 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