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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 reissue_activation(self, activation_key):
 """ Creates a new ``activation_key`` resetting activation timeframe when users let the previous key expire. :param activation_key: String containing the secret SHA1 activation key. """

        try:
            userena = self.get(activation_key=activation_key)
        except self.model.DoesNotExist:
            return False
        try:
            salt, new_activation_key = generate_sha1(userena.user.username)
            userena.activation_key = new_activation_key
            userena.save(using=self._db)
            userena.user.date_joined = get_datetime_now()
            userena.user.save(using=self._db)
            userena.send_activation_email()
            return True
        except Exception:
            return False