def cursor_down(self, count=None):
        cursor_position = self.pt_cursor_position
        margins = self.margins or Margins(0, self.lines - 1)

        # Ensure bounds.
        # (Following code is faster than calling `self.ensure_bounds`.)
        _, bottom = margins
        cursor_position.y = min(cursor_position.y + (count or 1),
                                bottom + self.line_offset + 1)

        self.max_y = max(self.max_y, cursor_position.y)
Calling ``reset_category`` with an empty list of metrics should
dataset/ETHPy150Open jonathanslenders/pymux/pymux/screen.py/BetterScreen.cursor_down--crossover with--dataset/ETHPy150Open bradmontgomery/django-redis-metrics/redis_metrics/tests/test_models.py/TestR.test_reset_category_with_no_metrics