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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 quote_xml(inStr):
    "Escape markup chars, but do not modify CDATA sections."
    if not inStr:
        return ''
    s1 = (isinstance(inStr, BaseStrType_) and inStr or '%s' % inStr)
    s2 = ''
    pos = 0
    matchobjects = CDATA_pattern_.finditer(s1)
    for mo in matchobjects:
        s3 = s1[pos:mo.start()]
        s2 += quote_xml_aux(s3)
        s2 += s1[mo.start():mo.end()]
        pos = mo.end()
    s3 = s1[pos:]
    s2 += quote_xml_aux(s3)
    return s2