def _getGraph(self, graph_name, fail_noexist=False):
graph = self._graphDict.get(graph_name)<EOL>if fail_noexist and graph is None:<EOL><INDENT>raise AttributeError("<STR_LIT>" % graph_name)<EOL><DEDENT>else:<EOL><INDENT>return graph<EOL><DEDENT>
Private method for returning graph object with name graph_name. 

        @param graph_name:   Graph Name
        @param fail_noexist: If true throw exception if there is no graph with
                             name graph_name.
        @return:             Graph Object or None