Search for comment :param:`id` and return a mapping of :attr:`fields`
        and values.

def get(self, id):
        """
        Search for comment :param:`id` and return a mapping of :attr:`fields`
        and values.
        """
        rv = self.db.execute(
            'SELECT * FROM comments WHERE id=?', (id, )).fetchone()
        if rv:
            return dict(zip(Comments.fields, rv))

        return None