def sub_group_lines(lines):
    """ Splits lines delimited by empty lines, groups split lines into lists.

    Args:
        lines (list): A list of lines seperated by empty lines.

    Returns:
        A list of lists of grouped lines.

    """
    groups, sub_group = [], []

    for line in lines:
        if len(line.rstrip()) > 0:
            sub_group.append(line.rstrip())
        else:
            groups.append(sub_group)
            sub_group = []

    if len(sub_group) > 0:
        groups.append(sub_group)

    return groups