def _dist(i_a, i_b):
    """
    Just a random distance metric used to decide if to compute mutual
    information for nearby epochs

    :param i_a: information for epoch a 
    :param i_b: information for epoch b
    :return: some notion of distance 
    """
    d = max(
        max(abs(i_a[0] - i_b[0])),
        max(abs(i_a[1] - i_b[1])),
    )
    return d