Selects from a set of given keys in an object and calls the corresponding
delegate. The difference to singleKey when invoked with a single key is
that keySwitch will not error out if the key is non-existent and may
trigger the delegate multiple times, if the JSON object has duplicate keys.
Selects from a set of given keys in an object and calls the corresponding delegate. The difference to singleKey when invoked with a single key is that keySwitch will not error out if the key is non-existent and may trigger the delegate multiple times, if the JSON object has duplicate keys.