func_code: def swap_unique_keys_values(d):
      new_dict = {}
      counter = {}
      for v in list(d.values()):
          if v not in counter:
              counter[v] = 0
          counter[v] += 1
      for k, v in list(d.items()):
          if counter[v] < 2:
              new_dict[v] = k
      return new_dict