According to their documentation https://cljdoc.org/d/io.github.camsaul/toucan2/1.0.511/api/toucan2.insert#insert-returning-instances!, insert-returning-instance! should return the inserted record back. However, it's returning nil. The same function works for postgres SQL so I am wondering if there is any configuration needs to be done for it to support mysql or they haven't provided the support for mysql?