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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 multi_session(self):
        ''' convert the multi_session param a number '''
        _val = 0
        if "multi_session" in self._dict:
            _val = self._dict["multi_session"]
            if str(_val).lower() == 'all':
                _val = -1

        return int(_val)