code: def consumption(self):
          
          consumption = defaultdict(float)
          for load in self.graph.nodes_by_attribute('load'):
              for sector, val in load.consumption.items():
                  consumption[sector] += val
  
          return pd.Series(consumption)
docs: Consumption in kWh per sector for whole grid
  
          Returns
          -------
          :pandas:`pandas.Series<series>`
              Indexed by demand sector