docs: def get_best_fit_parameters_grouped(self):
          """Returns a dictionary of the best fit."""
          result_dict = dict()
          result_dict['ocv'] = [parameters['ocv'] for parameters in
                                self.best_fit_parameters]
  
          for i in range(self.circuits):
              result_dict['t' + str(i)] = [parameters['t' + str(i)] for parameters
                                           in self.best_fit_parameters]
              result_dict['w' + str(i)] = [parameters['w' + str(i)] for parameters
                                           in self.best_fit_parameters]
          return result_dict