register_namespace_alias (OpenID::Message)

    # File lib/openid/message.rb, line 72
        def Message.register_namespace_alias(namespace_uri, alias_)
          if @@registered_aliases[alias_] == namespace_uri
              return
          end

          if @@registered_aliases.values.include?(namespace_uri)
            raise NamespaceAliasRegistrationError,
              'Namespace uri #{namespace_uri} already registered'
          end

          if @@registered_aliases.member?(alias_)
            raise NamespaceAliasRegistrationError,
              'Alias #{alias_} already registered'
          end

          @@registered_aliases[alias_] = namespace_uri
        end