def set_combine_stderr(self, combine):
data = bytes()<EOL>self.lock.acquire()<EOL>try:<EOL><INDENT>old = self.combine_stderr<EOL>self.combine_stderr = combine<EOL>if combine and not old:<EOL><INDENT>data = self.in_stderr_buffer.empty()<EOL><DEDENT><DEDENT>finally:<EOL><INDENT>self.lock.release()<EOL><DEDENT>if len(data) > <NUM_LIT:0>:<EOL><INDENT>self._feed(data)<EOL><DEDENT>return old<EOL>
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