code: def cone_search_lonlat(self, lon, lat, radius):
          
          if not lon.isscalar or not lat.isscalar or not radius.isscalar:
              raise ValueError('The longitude, latitude and radius must be '
                               'scalar Quantity objects')
          return healpix_cone_search(lon, lat, radius, self.nside, order=self.order)
docs: Find all the HEALPix pixels within a given radius of a longitude/latitude.
  
          Note that this returns all pixels that overlap, including partially, with
          the search cone. This function can only be used for a single lon/lat pair at
          a time, since different calls to the function may result in a different
          number of matches.
  
          Parameters
          ----------
          lon, lat : :class:`~astropy.units.Quantity`
              The longitude and latitude to search around
          radius : :class:`~astropy.units.Quantity`
              The search radius
  
          Returns
          -------
          healpix_index : `~numpy.ndarray`
              1-D array with all the matching HEALPix pixel indices.