code: def configs_for_reader(reader=None, ppp_config_dir=None):
      
      search_paths = (ppp_config_dir,) if ppp_config_dir else tuple()
      if reader is not None:
          if not isinstance(reader, (list, tuple)):
              reader = [reader]
          # check for old reader names
          new_readers = []
          for reader_name in reader:
              if reader_name.endswith('.yaml') or reader_name not in OLD_READER_NAMES:
                  new_readers.append(reader_name)
                  continue
  
              new_name = OLD_READER_NAMES[reader_name]
              # Satpy 0.11 only displays a warning
              # Satpy 0.13 will raise an exception
              raise ValueError("Reader name '{}' has been deprecated, use '{}' instead.".format(reader_name, new_name))
              # Satpy 0.15 or 1.0, remove exception and mapping
  
          reader = new_readers
          # given a config filename or reader name
          config_files = [r if r.endswith('.yaml') else r + '.yaml' for r in reader]
      else:
          reader_configs = glob_config(os.path.join('readers', '*.yaml'),
                                       *search_paths)
          config_files = set(reader_configs)
  
      for config_file in config_files:
          config_basename = os.path.basename(config_file)
          reader_configs = config_search_paths(
              os.path.join("readers", config_basename), *search_paths)
  
          if not reader_configs:
              # either the reader they asked for does not exist
              # or satpy is improperly configured and can't find its own readers
              raise ValueError("No reader(s) named: {}".format(reader))
  
          yield reader_configs
docs: Generator of reader configuration files for one or more readers
  
      Args:
          reader (Optional[str]): Yield configs only for this reader
          ppp_config_dir (Optional[str]): Additional configuration directory
              to search for reader configuration files.
  
      Returns: Generator of lists of configuration files