code: def create(dataset, symbol, degree):
          
  
          x_vals = dataset.data['T'].tolist()
          y_vals = dataset.data[symbol].tolist()
          coeffs = np.polyfit(x_vals, y_vals, degree)
  
          result = PolynomialModelT(dataset.material,
                                    dataset.names_dict[symbol],
                                    symbol, dataset.display_symbols_dict[symbol],
                                    dataset.units_dict[symbol],
                                    None, [dataset.name], coeffs)
  
          result.state_schema['T']['min'] = float(min(x_vals))
          result.state_schema['T']['max'] = float(max(x_vals))
  
          return result
docs: Create a model object from the data set for the property specified by
          the supplied symbol, using the specified polynomial degree.
  
          :param dataset: a DataSet object
          :param symbol: the symbol of the property to be described, e.g. 'rho'
          :param degree: the polynomial degree to use
  
          :returns: a new PolynomialModelT object