func_code: def swap_unique_keys_values(d):
      seen = []
      unseen = []
      for v in list(d.keys()):
          va = d[v]
          if va in unseen:
              seen.append(va)
          else:
              unseen.append(va)
          out = {v: k for k, v in list(d.items()) if v not in seen}
      return out