code: function getLastCharIndex(glyphs) {
      var maxGlyph = _.max(glyphs, 'unicode');
      if (maxGlyph) {
          return maxGlyph.unicode > 0xFFFF ? 0xFFFF : (maxGlyph.unicode || 0);
      } else {
          return 0xFFFF;
      }
  }
docs: get last glyph unicode