def normal(mu, sigma, random_state):
    """
    The probability density function of the normal distribution,
    first derived by De Moivre and 200 years later by both Gauss and Laplace independently.
    mu: float or array_like of floats
        Mean (“centre”) of the distribution.
    sigma: float or array_like of floats
           Standard deviation (spread or “width”) of the distribution.
    random_state: an object of numpy.random.RandomState
    """
    return random_state.normal(mu, sigma)
