# File lib/xml/util/xmlcanonicalizer.rb, line 111
        def add_inclusive_namespaces(prefix_list, element, visible_namespaces)
          namespaces = element.attributes()
          namespaces.each_attribute{|ns|
            if (ns.prefix=="xmlns")
              if (prefix_list.include?(ns.local_name()))
                visible_namespaces.push(NamespaceNode.new("xmlns:"+ns.local_name(), ns.value()))
              end
            end
          }
          parent = element.parent()
          add_inclusive_namespaces(prefix_list, parent, visible_namespaces) if (parent)
          visible_namespaces
        end