Removes from the list all the elements for which predicate unaryPredicate returns true. This reduces the list size by the amount of elements removed. Predicate unaryPredicate can be implemented as a function taking one argument of the same type as the list and returning a boolean. The function calls unaryPredicate.evaluate(x) for each element (where i is the element). Any of the elements in the list for which this returns true, is removed from the container.