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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 _err(self, msg, err=True):
 """Print useage and error before exiting."""

        severity = "FATAL" if err else "NOTE"
        txt = "".join([self.objdoc.doc,
                       "User's command-line:\n\n",
                       "  % go_plot.py {ARGS}\n\n".format(ARGS=" ".join(sys.argv[1:])),
                       "**{SEV}: {MSG}\n".format(SEV=severity, MSG=msg)])
        if err:
            raise RuntimeError(txt)
        sys.stdout.write(txt)
        sys.exit(0)