def mode(self, mode):
        """Sets the mode of this BraintreeGateway.


        :param mode: The mode of this BraintreeGateway.
        :type: str
        """
        allowed_values = ["test", "live"]
        if mode is not None and mode not in allowed_values:
            raise ValueError(
                "Invalid value for `mode` ({0}), must be one of {1}"
                .format(mode, allowed_values)
            )

        self._mode = mode