docs: def unique_file_name(base_name, extension=''):
      '''
      Creates a unique file name based on the specified base name.
  
      @base_name - The base name to use for the unique file name.
      @extension - The file extension to use for the unique file name.
  
      Returns a unique file string.
      '''
      idcount = 0
  
      if extension and not extension.startswith('.'):
          extension = '.%s' % extension
  
      fname = base_name + extension
  
      while os.path.exists(fname):
          fname = "%s-%d%s" % (base_name, idcount, extension)
          idcount += 1
  
      return fname