invalidate-argument Invalidate-argument (Conditional operator) Removes an argument from future consideration as a special data item. Takes 1 or more arguments... All: The argument to remove from the preceding argument list.
Using this is required if you intend to cycle through a list of non-recurring arguments in an event based on conditionals featuring arguments, like every-time-argument and when-argument. Otherwise, an argument remains valid even after it has been used once.
The default value is <any data>, not <argument>, so remember not to leave it on <any data>.