def printtime(t0: float, t1: float) -> str:
    """Return the elapsed time between t0 and t1 in h:m:s formatted string

    Parameters:
        t0: initial time
        t1: final time

    Returns:
        elapsed time
    """
    m, s = divmod(t1 - t0, 60)
    h, m = divmod(m, 60)
    fmt = '%d:%02d:%02d' % (h, m, s)

    return fmt