def load_ligands(self, fmt, ligands_file, *args, **kwargs):
        if fmt == 'mol2' and toolkit.backend == 'ob':
            if 'opt' in kwargs:
                kwargs['opt']['c'] = None
            else:
                kwargs['opt'] = {'c': None}
        new_pipe = self._ligand_pipe(toolkit.readfile(fmt, ligands_file, *args, **kwargs))
        self._pipe = chain(self._pipe, new_pipe) if self._pipe else new_pipe
:rtype: `SelectionSet`
dataset/ETHPy150Open oddt/oddt/oddt/virtualscreening.py/virtualscreening.load_ligands--crossover with--dataset/ETHPy150Open CountZer0/PipelineConstructionSet/python/maya/site-packages/pymel-1.0.3/pymel/core/nodetypes.py/ObjectSet.getIntersection