code: def appendGraph(self, graph_name, graph):
          
          self._graphDict[graph_name] = graph
          self._graphNames.append(graph_name)
          if not self.isMultigraph  and len(self._graphNames) > 1:
              raise AttributeError("Simple Munin Plugins cannot have more than one graph.")
docs: Utility method to associate Graph Object to Plugin.
          
          This utility method is for use in constructor of child classes for
          associating a MuninGraph instances to the plugin.
          
          @param graph_name:  Graph Name
          @param graph:       MuninGraph Instance