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Solve the following problem using Python, implementing the functions described below, one line at a time
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Description:
 def update_from_shiftfile(shiftfile,wcsname=None,force=False):
 """ Update headers of all images specified in shiftfile with shifts from shiftfile. Parameters shiftfile : str Filename of shiftfile. wcsname : str Label to give to new WCS solution being created by this fit. If a value of None is given, it will automatically use 'TWEAK' as the label. [Default =None] force : bool Update header even though WCS already exists with this solution or wcsname? [Default=False] """

    f = open(fileutil.osfn(shiftfile))
    shift_lines = [x.strip() for x in f.readlines()]
    f.close()

    # interpret header of shift file
    for line in shift_lines:
        if 'refimage' in line or 'reference' in line:
            refimage = line.split(':')[-1]
            refimage = refimage[:refimage.find('[wcs]')].lstrip()
            break

    # Determine the max length in the first column (filenames)
    fnames = []
    for row in shift_lines:
        if row[0] == '#': continue
        fnames.append(len(row.split(' ')[0]))
    fname_fmt = 'S{0}'.format(max(fnames))

    # Now read in numerical values from shiftfile
    type_list = {'names':('fnames','xsh','ysh','rot','scale','xrms','yrms'),
                 'formats':(fname_fmt,'f4','f4','f4','f4','f4','f4')}
    try:
        sdict = np.loadtxt(shiftfile,dtype=type_list,unpack=False)
    except IndexError:
        tlist = {'names':('fnames','xsh','ysh','rot','scale'),
                     'formats':(fname_fmt,'f4','f4','f4','f4')}
        s = np.loadtxt(shiftfile,dtype=tlist,unpack=False)
        sdict = np.zeros([s['fnames'].shape[0],],dtype=type_list)
        for sname in s.dtype.names:
            sdict[sname] = s[sname]

    for img in sdict:
        updatewcs_with_shift(img['fnames'], refimage, wcsname=wcsname,
                rot=img['rot'], scale=img['scale'],
                xsh=img['xsh'], ysh=img['ysh'],
                xrms=img['xrms'], yrms=img['yrms'],
                force=force)