code: def subs2seqs(self) -> Dict[str, List[str]]:
          
          subs2seqs = collections.defaultdict(list)
          nodes = find(self.find('sequences'), 'node')
          if nodes is not None:
              for seq in nodes:
                  subs2seqs['node'].append(strip(seq.tag))
          return subs2seqs
docs: A |collections.defaultdict| containing the node-specific
          information provided by XML `sequences` element.
  
          >>> from hydpy.auxs.xmltools import XMLInterface
          >>> from hydpy import data
          >>> interface = XMLInterface('single_run.xml', data.get_path('LahnH'))
          >>> series_io = interface.series_io
          >>> subs2seqs = series_io.writers[2].subs2seqs
          >>> for subs, seq in sorted(subs2seqs.items()):
          ...     print(subs, seq)
          node ['sim', 'obs']