func_code: def swap_unique_keys_values(d):
      A = False
      keyval = []
      new = {}
      done = {}
      for k, v in list(d.items()):
          keyval.append((v, k))
      done[keyval[0][0]] = A
      for each in keyval:
          if each[0] not in done:
              done[each[[0]]] = A
          else:
              done[each[0]] = True
          for each in kv:
              if not done[each[0]]:
                  new[each[0]] = each[1]
          return new