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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 doi_to_wos(wosclient, doi):
 """Convert DOI to WOS identifier."""

    results = query(wosclient, 'DO="%s"' % doi, './REC/UID', count=1)
    return results[0].lstrip('WOS:') if results else None