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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_files(self):
 """Return list of output files to be retrieved"""

        output_list = []

        pm_dict = self.get_dict()
        output_list.append(pm_dict['output_surface'])
        if pm_dict['target_volume'] != 0.0:
            output_list.append(pm_dict['output_surface'] + str(".cell"))

        return output_list