libssh2_channel_read_stderr(3) on Linux
The text 6b3a6db85f2f, 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_read_ex(3) calls