Man pages matching name memcached_set_sasl_callbacks in section 3:

memcached_set_sasl_callbacks.3.en	debian 10 / libmemcached-dev
memcached_set_sasl_callbacks.3.en	debian 11 / libmemcached-dev
memcached_set_sasl_callbacks.3.en	debian 12 / libmemcached-dev