remove unused import, vars shouldn't be mutable if not explicitly needed
remove unused import, vars shouldn't be mutable if not explicitly needed

cobalt-org/cobalt.rs,johannhof/cobalt.rs,cobalt-org/cobalt.rs,leesdolphin/cobalt.rs,leesdolphin/cobalt.rs,johannhof/cobalt.rs,leesdolphin/cobalt.rs,leesdolphin/cobalt.rs,johannhof/cobalt.rs,cobalt-org/cobalt.rs,johannhof/cobalt.rs,cobalt-org/cobalt.rs