def cohens_d(mu_1, mu_2, std):
    """

    Compute the standardized effect size as difference between the two means divided by the standard deviation.

    Parameters
    ----------
    mu_1 : float
        Mean of the first sample.
    mu_2 : float
        Mean of the second sample.
    std : float > 0
        Pooled standard deviation. It assumes that the variance of each population is the same.

    Returns
    -------
    effect_size : float
        Effect size as cohen's d coefficient
    """

    return (mu_1 - mu_2) / std