code: def devices(self) -> selectiontools.Selection:
          
          devices = self.find('devices')
          master = self
          while devices is None:
              master = master.master
              devices = master.find('devices')
          return _query_devices(devices)
docs: The additional devices defined for the respective `reader`
          or `writer` element contained within a |Selection| object. ToDo
  
          If the `reader` or `writer` element does not define its own additional
          devices, |XMLInterface.devices| of |XMLInterface| is used.
  
          >>> from hydpy.core.examples import prepare_full_example_1
          >>> prepare_full_example_1()
  
          >>> from hydpy import HydPy, TestIO, XMLInterface
          >>> hp = HydPy('LahnH')
          >>> with TestIO():
          ...     hp.prepare_network()
          ...     interface = XMLInterface('single_run.xml')
          >>> series_io = interface.series_io
          >>> for seq in (series_io.readers + series_io.writers):
          ...     print(seq.info, seq.devices.nodes, seq.devices.elements)
          all input data Nodes() \
  Elements("land_dill", "land_lahn_1", "land_lahn_2", "land_lahn_3")
          precipitation Nodes() Elements("land_lahn_1", "land_lahn_2")
          soilmoisture Nodes("dill") Elements("land_dill", "land_lahn_1")
          averaged Nodes() Elements()