'Returns true if this item is the end of a new group,
where groups mean that some attribute has changed.  The getter
can be None (the item itself changes), an attribute name like
``\'.attr\'``, a function, or a dict key or list index.'

def last_group(self, getter=None):

    if self.last:
        return True
    return self._compare_group(self.item, self.__next__, getter)
