def get_reviewable_hits(self, hit_type=None, status='Reviewable',
                            sort_by='Expiration', sort_direction='Ascending', 
                            page_size=10, page_number=1):
        """
        Retrieve the HITs that have a status of Reviewable, or HITs that
        have a status of Reviewing, and that belong to the Requester
        calling the operation.
        """
        params = {'Status' : status,
                  'SortProperty' : sort_by,
                  'SortDirection' : sort_direction,
                  'PageSize' : page_size,
                  'PageNumber' : page_number}

        # Handle optional hit_type argument
        if hit_type is not None:
            params.update({'HITTypeId': hit_type})

        return self._process_request('GetReviewableHITs', params, [('HIT', HIT),])
Retrieve the HITs that have a status of Reviewable, or HITs that
        have a status of Reviewing, and that belong to the Requester
        calling the operation.