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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 build(self):
 """Create and start up the internal workers."""


        # If there's no output tube, it means that this stage
        # is at the end of a fork (hasn't been linked to any stage downstream).
        # Therefore, create one output tube.
        if not self._output_tubes:
            self._output_tubes.append(self._worker_class.getTubeClass()())

        self._worker_class.assemble(
            self._worker_args,
            self._input_tube,
            self._output_tubes,
            self._size,
            self._disable_result,
            self._do_stop_task,
            )

        # Build all downstream stages.
        for stage in self._next_stages:
            stage.build()