How to use the drizzlepac.updatehdr function in drizzlepac

trans = np.hstack([trans/pscl, np.zeros((N,1)), np.ones((N,1))])
        elif sh[1] == 3:
            pscl = np.array([10.,10.,100])
            trans = np.hstack([trans/pscl, np.ones((N,1))])
        elif sh[1] == 4:
            pscl = np.array([10.,10.,100,100])
            trans = trans/pscl
        
        # Update direct WCS
        for ix, direct in enumerate(fine_visits):
            #direct = visits[ix]
            out_shift, out_rot = trans[ix,:2], trans[ix,2]
            out_scale = trans[ix,3]
            
            for file in direct['files']:
                updatehdr.updatewcs_with_shift(file, 
                                str('{0}_wcs.fits'.format(direct['product'])),
                                      xsh=out_shift[0], ysh=out_shift[1],
                                      rot=out_rot, scale=out_scale,
                                      wcsname='FINE', force=True,
                                      reusename=True, verbose=True,
                                      sciext='SCI')

            ### Bug in astrodrizzle? Dies if the FLT files don't have MJD-OBS
            ### keywords
            im = pyfits.open(file, mode='update')
            im[0].header['MJD-OBS'] = im[0].header['EXPSTART']
            im.flush()
        
        # Update grism WCS
        for i in range(len(all_groups)):
            direct = all_groups[i]['direct']

ysh=shift_dict[file][1],
                                        rot=0., scale=1.,
                                        wcsname='SHIFT', force=True,
                                        reusename=True, verbose=verbose,
                                        sciext='SCI')
        
        ### Bug in astrodrizzle? Dies if the FLT files don't have MJD-OBS
        ### keywords
        im = pyfits.open(file, mode='update')
        im[0].header['MJD-OBS'] = im[0].header['EXPSTART']
        im.flush()
        
        # Update paired grism exposures
        if file in grism_matches:
            for grism_file in grism_matches[file]:
                updatehdr.updatewcs_with_shift(grism_file, tweak_file,
                                              xsh=shift_dict[file][0],
                                              ysh=shift_dict[file][1],
                                              rot=0., scale=1.,
                                              wcsname='SHIFT', force=True,
                                              reusename=True, verbose=verbose,
                                              sciext='SCI')
                
                ### Bug in astrodrizzle? 
                im = pyfits.open(grism_file, mode='update')
                im[0].header['MJD-OBS'] = im[0].header['EXPSTART']
                im.flush()
    
    os.remove(tweak_file)

updatewcs.updatewcs(file, verbose=False)
        
    direct_flt = pyfits.open(direct['files'][0])
    ref_catalog = direct_flt['SCI',1].header['WCSNAME']
    
    #### User-defined shifts
    if xyscale is not None:
        # Use user-defined shifts
        xsh, ysh, rot, scale = xyscale
        
        tmp_wcs = '/tmp/{0}_tmpwcs.fits'.format(str(direct['product']))
        ext = len(wcs_hdu)-1
        wcs_hdu[ext].writeto(tmp_wcs, clobber=True)
        
        for file in grism['files']:
            updatehdr.updatewcs_with_shift(file, tmp_wcs,
                                      xsh=xsh,
                                      ysh=ysh,
                                      rot=rot, scale=scale,
                                      wcsname=ref_catalog, force=True,
                                      reusename=True, verbose=True,
                                      sciext='SCI')
            
            ### Bug in astrodrizzle? Dies if the FLT files don't have MJD-OBS
            ### keywords
            im = pyfits.open(file, mode='update')
            im[0].header['MJD-OBS'] = im[0].header['EXPSTART']
            im.flush()
        
        return True
        
    #### Get from WCS log file