+
+ # Pre-work hook.
+ #
+ # Used to inform `self` that operations will start.
+ # Specific streams can use this to prepare some resources.
+ #
+ # Is automatically invoked at the beginning of `with` structures.
+ #
+ # Do nothing by default.
+ fun start do end
+
+ # Post-work hook.
+ #
+ # Used to inform `self` that the operations are over.
+ # Specific streams can use this to free some resources.
+ #
+ # Is automatically invoked at the end of `with` structures.
+ #
+ # call `close` by default.
+ fun finish do close