This node simply takes an input set of data, and a Boolean switch. If the switch is true, the data is output. If the switch is false, the output is Empty List. This can be added to control the running of a script with master Boolean switches, or inline validation. In the case below, the List Length Validator confirms the input data has matching lengths, and the true output is used to control the flow in the Switch node.

List Length Validator

Take a list of lists and check whether all lists have the same length (same number of items in the list). This node is useful to run as part of a data export workflow (perhaps to Excel), to ensure the output lists are matching and thus have integrity.