code: def _add_properties(self, **kwargs):
          
          for k,v in kwargs.items():
              if k=='parallax':
                  self.obs.add_parallax(v)
              elif k in ['Teff', 'logg', 'feh', 'density']:
                  par = {k:v}
                  self.obs.add_spectroscopy(**par)
              elif re.search('_', k):
                  m = re.search('^(\w+)_(\w+)$', k)
                  prop = m.group(1)
                  tag = m.group(2)
                  self.obs.add_spectroscopy(**{prop:v, 'label':'0_{}'.format(tag)})
docs: Adds non-photometry properties to ObservationTree