libssh2_channel_flush_stderr(3) on Linux
The text 4f590d465d64, as Debian 12 (Bookworm), Debian 11 (Bullseye), Debian 10 (Buster), Debian 9 (Stretch), Debian 8 (Jessie), Debian 7 (Wheezy) shipped it.
convenience macro for libssh2_channel_flush_ex(3) calls