docs: public static Map<String,List<String>> findImages( File rootDir ) {
  		File files[] = rootDir.listFiles();
  		if( files == null )
  			return null;
  
  		List<File> imageDirectories = new ArrayList<>();
  		for( File f : files ) {
  			if( f.isDirectory() ) {
  				imageDirectories.add(f);
  			}
  		}
  		Map<String,List<String>> out = new HashMap<>();
  		for( File d : imageDirectories ) {
  			List<String> images = new ArrayList<>();
  
  			files = d.listFiles();
  			if( files == null )
  				throw new RuntimeException("Should be a directory!");
  
  			for( File f : files ) {
  				if( f.isHidden() || f.isDirectory() || f.getName().endsWith(".txt") ) {
  					continue;
  				}
  
  				images.add( f.getPath() );
  			}
  
  			String key = d.getName().toLowerCase();
  
  			out.put(key,images);
  		}
  
  		return out;
  	}