Man pages matching name wslay_event_config_set_callbacks in section 3:

wslay_event_config_set_callbacks.3.en	debian 10 / libwslay-doc
wslay_event_config_set_callbacks.3.en	debian 11 / libwslay-doc
wslay_event_config_set_callbacks.3.en	debian 12 / libwslay-doc