callback parameters

On line 35 "(callback datom tx-data key)" in datascript_menu.cljs, what is the purpose of parameters: "datom", "tx-data" and "key"?
Everything works perfectly without them.
Same for parameters on line 64 "(fn [datom tx-data key](rum/request-render comp))]". It also works without parameters like this "(fn [](rum/request-render comp))".

Thanks
Enes
