@classmethod
def _get_final_length(cls, l):
    """
        Returns the total length of the deepest lists inside ``ŀ``.

        :arg list l: A nested list.
        :returns: The total length of the deepest lists inside ``l``.
        :rtype: int

        >>> TableDict._get_final_length([['a', [1, 2, 3]], ['b', [4, 5]]])
        5
        """
    total = 0
    for item in l:
        if isinstance(item, (list, tuple)):
            header, group = item
            total += cls._get_final_length(group)
        else:
            total += 1
    return total
