docs: def find_resources_to_get(lecture, file_formats, resource_filter, ignored_formats=None):
      """
      Select formats to download.
      """
      resources_to_get = []
  
      if ignored_formats is None:
          ignored_formats = []
  
      if len(ignored_formats):
          logging.info("The following file formats will be ignored: " + ",".join(ignored_formats))
  
      for fmt, resources in iteritems(lecture):
          fmt0 = fmt
  
          short_fmt = None
          if '.' in fmt:
              short_fmt = fmt.split('.')[1]
  
          if fmt in ignored_formats or (short_fmt != None and short_fmt in ignored_formats) :
              continue
  
          if fmt in file_formats or (short_fmt != None and short_fmt in file_formats) or 'all' in file_formats:
              for r in resources:
                  if resource_filter and r[1] and not re.search(resource_filter, r[1]):
                      logging.debug('Skipping b/c of rf: %s %s',
                                    resource_filter, r[1])
                      continue
                  resources_to_get.append((fmt0, r[0], r[1]))
          else:
              logging.debug(
                  'Skipping b/c format %s not in %s', fmt, file_formats)
  
      return resources_to_get