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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 _set_default_headers(self):
 """ Create some default headers that should be sent along with every HTTP response """

        self.headers.setdefault('Date', self.get_current_time)
        self.headers.setdefault('Server', self.SERVER_INFO)
        self.headers.setdefault('Content-Length', "%d" % len(self.message))
        if self.app.enabled('x-powered-by'):
            self.headers.setdefault('X-Powered-By', 'Growler')