code: def _interpolate_stream_track_aA(self):
          
          if hasattr(self,'_interpolatedObsTrackAA'):
              return None #Already did this
          #Calculate 1D meanOmega on a fine grid in angle and interpolate
          if not hasattr(self,'_interpolatedThetasTrack'):
              self._interpolate_stream_track()
          dmOs= numpy.array([self.meanOmega(da,oned=True,use_physical=False) 
                            for da in self._interpolatedThetasTrack])
          self._interpTrackAAdmeanOmegaOneD=\
              interpolate.InterpolatedUnivariateSpline(\
              self._interpolatedThetasTrack,dmOs,k=3)
          #Build the interpolated AA
          self._interpolatedObsTrackAA=\
              numpy.empty((len(self._interpolatedThetasTrack),6))
          for ii in range(len(self._interpolatedThetasTrack)):
              self._interpolatedObsTrackAA[ii,:3]=\
                  self._progenitor_Omega+dmOs[ii]*self._dsigomeanProgDirection\
                  *self._sigMeanSign   
              self._interpolatedObsTrackAA[ii,3:]=\
                  self._progenitor_angle+self._interpolatedThetasTrack[ii]\
                  *self._dsigomeanProgDirection*self._sigMeanSign
              self._interpolatedObsTrackAA[ii,3:]=\
                  numpy.mod(self._interpolatedObsTrackAA[ii,3:],2.*numpy.pi)
          return None
docs: Build interpolations of the stream track in action-angle coordinates