code: def load_hdf(cls, filename, path='', ic=None):
          
          store = pd.HDFStore(filename)
          try:
              samples = store[path+'/df']
              attrs = store.get_storer(path+'/df').attrs
          except:
              store.close()
              raise
          df = store[path+'/df']
          new = cls.from_df(df)
  
          if ic is None:
              ic = get_ichrone('mist')
  
          new.define_models(ic, N=attrs.N, index=attrs.index)
          new.spectroscopy = attrs.spectroscopy
          new.parallax = attrs.parallax
          store.close()
          return new
docs: Loads stored ObservationTree from file.
  
          You can provide the isochrone to use; or it will default to MIST
  
          TODO: saving and loading must be fixed!  save ic type, bands, etc.