docs: def load_from_xml(baseURI, rels_item_xml):
          """
          Return |_SerializedRelationships| instance loaded with the
          relationships contained in *rels_item_xml*. Returns an empty
          collection if *rels_item_xml* is |None|.
          """
          srels = _SerializedRelationships()
          if rels_item_xml is not None:
              rels_elm = parse_xml(rels_item_xml)
              for rel_elm in rels_elm.Relationship_lst:
                  srels._srels.append(_SerializedRelationship(baseURI, rel_elm))
          return srels