get_sreg_ns (OpenID)

    # File lib/openid/extensions/sreg.rb, line 45
        def OpenID.get_sreg_ns(message)
          [NS_URI_1_1, NS_URI_1_0].each{|ns|
            if message.namespaces.get_alias(ns)
              return ns
            end
          }
          # try to add an alias, since we didn't find one
          ns = NS_URI_1_1
          begin
            message.namespaces.add_alias(ns, 'sreg')
          rescue IndexError
            raise NamespaceError
          end
          return ns
        end