code: def export(self, elec_file):
          
          elec_file = Path(elec_file)
          if elec_file.suffix == '.csv':
              sep = ', '
          elif elec_file.suffix == '.sfp':
              sep = ' '
  
          with elec_file.open('w') as f:
              for one_chan in self.chan:
                  values = ([one_chan.label, ] +
                            ['{:.3f}'.format(x) for x in one_chan.xyz])
                  line = sep.join(values) + '\n'
                  f.write(line)
docs: Export channel name and location to file.
  
          Parameters
          ----------
          elec_file : Path or str
              path to file where to save csv