# File lib/openid/consumer.rb, line 220
    def begin(openid_identifier, anonymous=false)
      manager = discovery_manager(openid_identifier)
      service = manager.get_next_service(&method(:discover))

      if service.nil?
        raise DiscoveryFailure.new("No usable OpenID services were found "\
                                   "for #{openid_identifier.inspect}", nil)
      else
        begin_without_discovery(service, anonymous)
      end
    end