insert_before (REXML::Parent)

    # File src/rexml/parent.rb, line 82
                    def insert_before( child1, child2 )
                            if child1.kind_of? String
                                    child1 = XPath.first( self, child1 )
                                    child1.parent.insert_before child1, child2
                            else
                                    ind = index(child1)
                                    child2.parent.delete(child2) if child2.parent
                                    @children[ind,0] = child2
                                    child2.parent = self
                            end
                            self
                    end