code: def read_hlet_wcs(filename, ext):
      
      hstwcs = wcsutil.HSTWCS(filename, ext=ext)
      if hstwcs.naxis1 is None:
          hstwcs.naxis1 = int(hstwcs.wcs.crpix[0] * 2.)  # Assume crpix is center of chip
          hstwcs.naxis2 = int(hstwcs.wcs.crpix[1] * 2.)
  
      return hstwcs
docs: Insure `stwcs.wcsutil.HSTWCS` includes all attributes of a full image WCS.
  
      For headerlets, the WCS does not contain information about the size of the
      image, as the image array is not present in the headerlet.