code: def get_hall_carrier_concentration(self):
          
          result = {temp: [] for temp in self._hall}
          for temp in self._hall:
              for i in self._hall[temp]:
                  trace = (i[1][2][0] + i[2][0][1] + i[0][1][2]) / 3.0
                  if trace != 0.0:
                      result[temp].append(1e-6 / (trace * constants.e))
                  else:
                      result[temp].append(0.0)
          return result
docs: gives the Hall carrier concentration (in cm^-3). This is the trace of
          the Hall tensor (see Boltztrap source code) Hall carrier concentration
          are not always exactly the same than carrier concentration.
  
          Returns
              a dictionary {temp:[]} with an array of Hall carrier concentration
              (in cm^-3) at each temperature The array relates to each step of
              electron chemical potential