<SYSTEM_TASK:>
Solve the following problem using Python, implementing the functions described below, one line at a time
<END_TASK>
<USER_TASK:>
Description:
 def get_without(self, fragments, use_lookup=None):
 """Return self without the specified fragments. Args: fragments: Either a list of :class:`~chemcoord.Cartesian` or a :class:`~chemcoord.Cartesian`. use_lookup (bool):
 Use a lookup variable for :meth:`~chemcoord.Cartesian.get_bonds`. The default is specified in ``settings['defaults']['use_lookup']`` Returns: list: List containing :class:`~chemcoord.Cartesian`. """

        if use_lookup is None:
            use_lookup = settings['defaults']['use_lookup']

        if pd.api.types.is_list_like(fragments):
            for fragment in fragments:
                try:
                    index_of_all_fragments |= fragment.index
                except NameError:
                    index_of_all_fragments = fragment.index
        else:
            index_of_all_fragments = fragments.index
        missing_part = self.loc[self.index.difference(index_of_all_fragments)]
        missing_part = missing_part.fragmentate(use_lookup=use_lookup)
        return sorted(missing_part, key=len, reverse=True)