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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 write_transform(transform, filename):
 """ Write ANTsTransform to file ANTsR function: `writeAntsrTransform` Arguments --------- transform : ANTsTransform transform to save filename : string filename of transform (file extension is ".mat" for affine transforms) Returns ------- N/A Example ------- """

    filename = os.path.expanduser(filename)
    libfn = utils.get_lib_fn('writeTransform%s' % (transform._libsuffix))
    libfn(transform.pointer, filename)