code: def _get_filtered_study_ids(shard, include_aliases=False):
      
      from peyotl.phylesystem.helper import DIGIT_PATTERN
      k = shard.get_doc_ids()
      if shard.has_aliases and (not include_aliases):
          x = []
          for i in k:
              if DIGIT_PATTERN.match(i) or ((len(i) > 1) and (i[-2] == '_')):
                  pass
              else:
                  x.append(i)
          return x
docs: Optionally filters out aliases from standard doc-id list