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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 _output_terms(self):
 """ A list of terms that are outputs of this pipeline. Includes all terms registered as data outputs of the pipeline, plus the screen, if present. """

        terms = list(six.itervalues(self._columns))
        screen = self.screen
        if screen is not None:
            terms.append(screen)
        return terms