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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 postprocess(self):
 """ Postprocessing includes renaming and gzipping where necessary. """

        # Add suffix to all sub_dir/{items}
        for path in self.neb_dirs:
            for f in VASP_NEB_OUTPUT_SUB_FILES:
                f = os.path.join(path, f)
                if os.path.exists(f):
                    if self.final and self.suffix != "":
                        shutil.move(f, "{}{}".format(f, self.suffix))
                    elif self.suffix != "":
                        shutil.copy(f, "{}{}".format(f, self.suffix))

        # Add suffix to all output files
        for f in VASP_NEB_OUTPUT_FILES + [self.output_file]:
            if os.path.exists(f):
                if self.final and self.suffix != "":
                    shutil.move(f, "{}{}".format(f, self.suffix))
                elif self.suffix != "":
                    shutil.copy(f, "{}{}".format(f, self.suffix))