@NotNull
    @Override
    public Boolean join(@NotNull List<? extends Boolean> ins) {
      if (ins.isEmpty()) {
        return false;
      }
      boolean b = true;
      for (boolean candidate : ins) {
        b &= candidate;
      }
      return b;
    }
@NotNull
    @Override
    public Boolean join(@NotNull List<? extends Boolean> ins)