# File lib/xml/dom/core.rb, line 627
      def _searchID(value, ids = nil)
        if ids.nil?
          doc = nil
          if nodeType == DOCUMENT_NODE
            doc = self
          elsif !ownerDocument.nil?
            doc = ownerDocument
          else
            return nil
          end
          ids = doc._getIDAttrs
        end
        if nodeType == ELEMENT_NODE && _getIDVals(ids).include?(value)
          return self
        elsif !@children.nil?
          @children.each do |node|
            if !(match = node._searchID(value, ids)).nil?
              return match
            end
          end
        end
        return nil
      end