A CallbackAsync accesses and modifies data during the optimization via the ContextAsync.
See the section on active bindings for a list of modifiable objects.
See callback_async() for a list of stages which access ContextAsync.
mlr3misc::Context -> ContextAsync
instance(OptimInstance).
optimizer(Optimizer).
result(data.table::data.table)
The result of the optimization.
Changes to $instance and $optimizer in the stages executed on the workers are not reflected in the main process.