docs: def chain(tree, edition_number):
          """
          Args:
              tree (dict): Tree history of all editions of a piece.
              edition_number (int): The edition number to check for.
                  In the case of a piece (master edition), an empty
                  string (``''``) or zero (``0``) can be passed.
  
          Returns:
              list: The chain of ownsership of a particular
              edition of the piece ordered by time.
  
          """
          # return the chain for an edition_number sorted by the timestamp
          return sorted(tree.get(edition_number, []), key=lambda d: d['timestamp_utc'])