new_contents: import re
  from os import walk, makedirs, listdir, unlink
  from shutil import copyfile
  from os.path import join, basename, dirname
  from .__main__ import OUTPUT
  
  
  FILENAME_RE = re.compile(r'[A-Za-z_]+\.png')
  
  
  def get_filenames():
      filenames = (
          join(dirpath, filename)
          for dirpath, _, filenames in list(walk(OUTPUT))
          for filename in filenames
      )
  
      yield from (
          filename
          for filename in filenames
          if 'old' not in filename and FILENAME_RE.match(basename(filename))
      )
  
  
  def main():
      collated = join(dirname(OUTPUT), 'collated')
  
      for filename in listdir(collated):
          unlink(join(collated, filename))
  
      makedirs(collated, exist_ok=True)
  
      for src in get_filenames():
          dest = join(collated, basename(src))
          print(src, '->', dest)
          copyfile(src, dest)
  
  if __name__ == '__main__':
      main()
  
subject: Add helper utility