code: def _best_fit_font_size(self, max_size):
          
          predicate = self._fits_inside_predicate
          sizes = _BinarySearchTree.from_ordered_sequence(
              range(1, int(max_size)+1)
          )
          return sizes.find_max(predicate)
docs: Return the largest whole-number point size less than or equal to
          *max_size* that this fitter can fit.