code: def get_capacity_grav(self, min_voltage=None, max_voltage=None,
                            use_overall_normalization=True):
          
          pairs_in_range = self._select_in_voltage_range(min_voltage,
                                                         max_voltage)
          normalization_mass = self.normalization_mass \
              if use_overall_normalization or len(pairs_in_range) == 0 \
              else pairs_in_range[-1].mass_discharge
          return sum([pair.mAh for pair in pairs_in_range]) / normalization_mass
docs: Get the gravimetric capacity of the electrode.
  
          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:
              Gravimetric capacity in mAh/g across the insertion path (a subset
              of the path can be chosen by the optional arguments).