code: func (crng ChiSquaredGenerator) ChiSquared(freedom int64) float64 {
  	if freedom <= 0 {
  		panic(fmt.Sprintf("Invalid parameter freedom: %d (freedom > 0)", freedom))
  	}
  	return crng.chisquared(freedom)
  }
docs: // ChiSquared returns a random number of chi-squared distribution (freedom > 0)