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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 build_reference_wcs(inputs, sciname='sci'):
 """Create the reference WCS based on all the inputs for a field"""

    # start by creating a composite field-of-view for all inputs
    wcslist = []
    for img in inputs:
        nsci = countExtn(img)
        for num in range(nsci):
            extname = (sciname, num + 1)
            if sciname == 'sci':
                extwcs = wcsutil.HSTWCS(img, ext=extname)
            else:
                # Working with HDRLET as input and do the best we can...
                extwcs = read_hlet_wcs(img, ext=extname)

            wcslist.append(extwcs)

    # This default output WCS will have the same plate-scale and orientation
    # as the first chip in the list, which for WFPC2 data means the PC.
    # Fortunately, for alignment, this doesn't matter since no resampling of
    # data will be performed
    outwcs = utils.output_wcs(wcslist)

    return outwcs