func_code: def swap_unique_keys_values(d):
      z = []
      l = []
      for c in list(d.items()):
          l.append(c[1])
      for c in l:
          if l.count(c) == 1:
              z.append(c)
      d1 = {v: k for k, v in list(d.items()) if v in z}
      return d1