deferred class interface P_CONTAINER[G] feature(s) from P_CONTAINER -- Status count: INTEGER -- Number of items in the container. ensure positive: Result >= 0 is_empty: BOOLEAN -- Is the container empty? is_readable: BOOLEAN -- Is the container currently readable? is_writable: BOOLEAN -- Is the container currently writable? item: G -- Current item. require readable: is_readable; not_empty: not is_empty feature(s) from P_CONTAINER -- Update reset -- Remove all objects from the container. require writable: is_writable ensure done: is_empty feature(s) from P_CONTAINER -- Output out: STRING -- String representation. ensure is_copy: -- new string feature(s) from P_CONTAINER -- Utility is_void (x: ANY): BOOLEAN -- Void assertion for generic parameters. invariant empty: is_empty = count = 0; end of deferred P_CONTAINER[G]