code: def get_energy_density(self, min_voltage=None, max_voltage=None,
                             use_overall_normalization=True):
          
          return self.get_capacity_vol(min_voltage, max_voltage,
                                       use_overall_normalization) \
              * self.get_average_voltage(min_voltage, max_voltage)
docs: Args:
              min_voltage (float): The minimum allowable voltage for a given
                  step.
              max_voltage (float): The maximum allowable voltage allowable for a
                  given step.
              use_overall_normalization (booL): If False, normalize by the
                  discharged state of only the voltage pairs matching the voltage
                  criteria. if True, use default normalization of the full
                  electrode path.
  
          Returns:
              Energy density in Wh/L across the insertion path (a subset of the
              path can be chosen by the optional arguments).