code: def fitted_parameters(self):
          
          if hasattr(self,'_fitted_parameters'): return self._fitted_parameters
          if not self.fitting_parameters: return tuple()
          if self.options['fit_function'] == 'lmfit':
              return tuple( self.curve_fit.params[key].value for key in sorted(self.curve_fit.params) )
          else:
              return tuple(self.curve_fit[0])
docs: A tuple of fitted values for the `scipy_data_fitting.Fit.fitting_parameters`.
  
          The values in this tuple are not scaled by the prefix,
          as they are passed back to `scipy_data_fitting.Fit.function`,
          e.g. in most standard use cases these would be the SI values.
  
          If no fitting parameters were specified, this will just return an empty tuple.