code: def _old_skyline(xs):
      # naive implementation, O(n2)
      return {
          (s, c)
          for s, c in xs
          if not any(
              s2 >= s and c2 >= c for s2, c2 in xs if (s, c) != (s2, c2)
          )
      }
  
imports: import itertools
  import unittest
  from typing import Iterable, Mapping
  import numpy
  import pandas
  from pykeen.datasets import Dataset, Nations
  from pykeen.datasets import analysis
  from pykeen.triples import analysis
  from pykeen.typing import LABEL_HEAD, LABEL_TAIL
label_desc: Use image node_id 1 for calling a global function with example usage: _old_skyline(xs) and returns: unknown