code: def load_pygame(filename, *args, **kwargs):
      
      kwargs['image_loader'] = pygame_image_loader
      return pytmx.TiledMap(filename, *args, **kwargs)
docs: Load a TMX file, images, and return a TiledMap class
  
      PYGAME USERS: Use me.
  
      this utility has 'smart' tile loading.  by default any tile without
      transparent pixels will be loaded for quick blitting.  if the tile has
      transparent pixels, then it will be loaded with per-pixel alpha.  this is
      a per-tile, per-image check.
  
      if a color key is specified as an argument, or in the tmx data, the
      per-pixel alpha will not be used at all. if the tileset's image has colorkey
      transparency set in Tiled, the util_pygam will return images that have their
      transparency already set.
  
      TL;DR:
      Don't attempt to convert() or convert_alpha() the individual tiles.  It is
      already done for you.