loopback?

# File lib/ipaddr.rb, line 263
  def loopback?
    case @family
    when Socket::AF_INET
      @addr & 0xff000000 == 0x7f000000
    when Socket::AF_INET6
      @addr == 1
    else
      raise AddressFamilyError, "unsupported address family"
    end
  end