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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 mol(self):
 """ Return record in MOL format """

        if self._mol is None:
            apiurl = 'http://www.chemspider.com/MassSpecAPI.asmx/GetRecordMol?csid=%s&calc3d=false&token=%s' % (self.csid,TOKEN)
            response = urlopen(apiurl)
            tree = ET.parse(response)
            self._mol = tree.getroot().text
        return self._mol