# File src/rexml/document.rb, line 66
                def add( child )
                        if child.kind_of? XMLDecl
                                @children.unshift child
                        elsif child.kind_of? DocType
                                if @children[0].kind_of? XMLDecl
                                        @children[1,0] = child
                                else
                                        @children.unshift child
                                end
                                child.parent = self
                        else
                                rv = super
                                raise "attempted adding second root element to document" if @elements.size > 1
                                rv
                        end
                end