Part of lp.services.orderingcheck View In Hierarchy
Use this if to verify that a series of items you are iterating over is in some expected order. Any items that are not ordered the way you expect are reported to a customizable failure handler; it raises an error by default.
|Method||__init__||Define an ordering. Parameters are as for sorted().|
itemcomes after the previous item, if any.
Call this with each of the items in the sequence as you process
them. If any of the items is not at its right place in the
sequence, this will call
fail with that item.