code: def refs_equal(olditem, newitem):
          
          oldrefs = olditem.references
          newrefs = newitem.references
  
          ref_equal = lambda oldref, newref: True if (len(oldref) == len(newref)) and all(
              x in oldref for x in newref) else False
          if len(oldrefs) == len(newrefs) and all(
                  any(ref_equal(oldref, newref) for oldref in oldrefs) for newref in newrefs):
              return True
          else:
              return False
docs: tests for exactly identical references