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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 add_exception_handler(self, exception_handler):
 # type: (AbstractExceptionHandler) -> None """Checks the type before adding it to the exception_handlers instance variable. :param exception_handler: Exception Handler instance. :type exception_handler: ask_sdk_runtime.dispatch_components.exception_components.AbstractExceptionHandler :raises: :py:class:`ask_sdk_runtime.exceptions.DispatchException` if a null input is provided or if the input is of invalid type """

        if exception_handler is None or not isinstance(
                exception_handler, AbstractExceptionHandler):
            raise DispatchException(
                "Input is not an AbstractExceptionHandler instance")
        self._exception_handlers.append(exception_handler)