code: def relpath(dataset_uri, item_identifier):
      
      dataset = dtoolcore.DataSet.from_uri(dataset_uri)
      try:
          props = dataset.item_properties(item_identifier)
      except KeyError:
          click.secho(
              "No such item in dataset: {}".format(item_identifier),
              fg="red",
              err=True
          )
          sys.exit(21)
      click.secho(props["relpath"])
docs: Return relpath associated with the item.