def appendSubgraph(self, parent_name,  graph_name, graph):
if not self.isMultigraph:<EOL><INDENT>raise AttributeError("<STR_LIT>")<EOL><DEDENT>if parent_name in self._graphDict:<EOL><INDENT>if parent_name not in self._subgraphDict:<EOL><INDENT>self._subgraphDict[parent_name] = {}<EOL>self._subgraphNames[parent_name] = []<EOL><DEDENT>self._subgraphDict[parent_name][graph_name] = graph<EOL>self._subgraphNames[parent_name].append(graph_name)<EOL><DEDENT>else:<EOL><INDENT>raise AttributeError("<STR_LIT>"<EOL>% (parent_name,  graph_name))<EOL><DEDENT>
Utility method to associate Subgraph Instance to Root Graph Instance.

        This utility method is for use in constructor of child classes for 
        associating a MuninGraph Subgraph instance with a Root Graph instance.

        @param parent_name: Root Graph Name
        @param graph_name:  Subgraph Name
        @param graph:       MuninGraph Instance