def sacks(tcph):
    """Returns the sacks in the tcp header.

    Args:
        tcph: The parsed TCP header.

    Returns:
        The list of sacks in the form of (start seq, end seq).
    """
    sack_list = []
    for name, val in tcph.options:
        if name != 'SAck':
            continue
        sack_list.append((val[0], val[1]))
    return sack_list