Print statistical information via the provided logger

        Parameters
        ----------
        logger : logging.Logger
            logger created using logging.getLogger()

def log_info(self, logger):
        """Print statistical information via the provided logger

        Parameters
        ----------
        logger : logging.Logger
            logger created using logging.getLogger()
        """
        logger.info('#words in training set: %d' % self._words_in_train_data)
        logger.info("Vocab info: #words %d, #tags %d #rels %d" % (self.vocab_size, self.tag_size, self.rel_size))