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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 _tostr(self,obj):
 """ converts a object to list, if object is a list, it creates a comma seperated string. """

        if not obj:
            return ''
        if isinstance(obj, list):
            return ', '.join(map(self._tostr, obj))
        return str(obj)