All hooks now return an instance of a hook specific Results class, which can return data, directives or rejection from a hook, depending on the hook type.

All supported Smart and Supervisor Contracts directives are now instructed by returning an instance of a specific Directive class via the hook Result class attribute. The vault methods used to instruct directives have been removed.

Raising exceptions are not supported in any Contract hooks, however, some hooks, i.e. pre_posting_hook can return Rejection to reject the Vault data change proposed.

The pre_parameter_change_hook can now only return Rejection or None result, the ability to return modified Parameter class instances has been removed.

Both the activation_hook and conversion_hook now return account or plan schedules; this replaces the execution_schedules hook.

The deactivation_hook can return the optional Rejection, which would reject the account closure.