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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 check_input(self, obj):
 """ Performs checks on the input object. Raises an exception if unsupported. :param obj: the object to check :type obj: object """

        if isinstance(obj, str):
            return
        if isinstance(obj, unicode):
            return
        raise Exception("Unsupported class: " + self._input.__class__.__name__)