new_contents: from astrometry.util.fits import fits_table
  from astrometry.libkd.spherematch import tree_build
  import numpy as np
  import os
  import argparse
  
  if __name__ == '__main__':
      parser = argparse.ArgumentParser()
      parser.add_argument('infn', help='Input filename (eg, skyscales_ccds.fits)')
      parser.add_argument('outfn', help='Output filename (eg, sky-scales.kd.fits)')
      opt = parser.parse_args()
      infn = opt.infn
      outfn = opt.outfn
      S = fits_table(infn)
      ekd = tree_build(np.atleast_2d(S.expnum.copy()).T.astype(float),
                       nleaf=60, bbox=False, split=True)
      ekd.set_name('expnum')
      ekd.write('ekd.fits')
      cmd = 'fitsgetext -i ekd.fits -o ekd-%02i -a -M'
      rtn = os.system(cmd)
      assert(rtn == 0)
      cmd = 'cat %s ekd-0[1-6] > %s' % (infn, outfn)
      rtn = os.system(cmd)
      assert(rtn == 0)
      return 0
  
subject: add script to create sky-template kdtree