Adjust keywords, if needed.

def _adj_item_marks(self):
        """Adjust keywords, if needed."""
        if 'item_marks' in self.kws:
            # Process GO IDs specified in item_marks
            goids = self._get_goids(self.kws['item_marks'])
            # item_marks can take a list of GO IDs on cmdline or in a file.
            #     --item_marks=GO:0043473,GO:0009987
            #     --item_marks=item_marks.txt
            if goids:
                self.kws['item_marks'] = {go:'>' for go in goids}
            else:
                raise Exception("NO GO IDs FOUND IN item_marks")