Set whether stderr should be combined into stdout on this channel.
        The default is ``False``, but in some cases it may be convenient to
        have both streams combined.

        If this is ``False``, and `exec_command` is called (or ``invoke_shell``
        with no pty), output to stderr will not show up through the `recv`
        and `recv_ready` calls.  You will have to use `recv_stderr` and
        `recv_stderr_ready` to get stderr output.

        If this is ``True``, data will never show up via `recv_stderr` or
        `recv_stderr_ready`.

        :param bool combine:
            ``True`` if stderr output should be combined into stdout on this
            channel.
        :return: the previous setting (a `bool`).

        .. versionadded:: 1.1

def set_combine_stderr(self, combine):
        """
        Set whether stderr should be combined into stdout on this channel.
        The default is ``False``, but in some cases it may be convenient to
        have both streams combined.

        If this is ``False``, and `exec_command` is called (or ``invoke_shell``
        with no pty), output to stderr will not show up through the `recv`
        and `recv_ready` calls.  You will have to use `recv_stderr` and
        `recv_stderr_ready` to get stderr output.

        If this is ``True``, data will never show up via `recv_stderr` or
        `recv_stderr_ready`.

        :param bool combine:
            ``True`` if stderr output should be combined into stdout on this
            channel.
        :return: the previous setting (a `bool`).

        .. versionadded:: 1.1
        """
        data = bytes()
        self.lock.acquire()
        try:
            old = self.combine_stderr
            self.combine_stderr = combine
            if combine and not old:
                # copy old stderr buffer into primary buffer
                data = self.in_stderr_buffer.empty()
        finally:
            self.lock.release()
        if len(data) > 0:
            self._feed(data)
        return old