Describe the order in which groups move

    Arguments
    ---------
    num_groups : int

    Returns
    -------
    np.ndarray
        Matrix P* - size (g-by-g)

def generate_p_star(num_groups):
    """Describe the order in which groups move

    Arguments
    ---------
    num_groups : int

    Returns
    -------
    np.ndarray
        Matrix P* - size (g-by-g)
    """
    p_star = np.eye(num_groups, num_groups)
    rd.shuffle(p_star)
    return p_star