code: def skycoord_to_healpix(self, skycoord, return_offsets=False):
          
          if self.frame is None:
              raise NoFrameError("skycoord_to_healpix")
          skycoord = skycoord.transform_to(self.frame)
          representation = skycoord.represent_as(UnitSphericalRepresentation)
          lon, lat = representation.lon, representation.lat
          return self.lonlat_to_healpix(lon, lat, return_offsets=return_offsets)
docs: Convert celestial coordinates to HEALPix indices (optionally with offsets).
  
          Note that this method requires that a celestial frame was specified when
          initializing HEALPix. If you don't know or need the celestial frame, you
          can instead use :meth:`~astropy_healpix.HEALPix.lonlat_to_healpix`.
  
          Parameters
          ----------
          skycoord : :class:`~astropy.coordinates.SkyCoord`
              The celestial coordinates to convert
          return_offsets : bool
              If `True`, the returned values are the HEALPix pixel as well as
              ``dx`` and ``dy``, the fractional positions inside the pixel. If
              `False` (the default), only the HEALPix pixel is returned.
  
          Returns
          -------
          healpix_index : `~numpy.ndarray`
              1-D array of HEALPix indices
          dx, dy : `~numpy.ndarray`
              1-D arrays of offsets inside the HEALPix pixel in the range [0:1] (0.5
              is the center of the HEALPix pixels). This is returned if
              ``return_offsets`` is `True`.