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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 getPrevUrl(self, url, data):
 """Decrease index.html number."""

        mo = compile(r"index(\d+)\.html").search(url)
        num = int(mo.group(1)) - 1
        prefix = url.rsplit('/', 1)[0]
        return "%s/index%d.html" % (prefix, num)