TYPEOF is available since version 1.0.0.
Gets the type of an element.
TYPEOF function consumes the top element on the stack and pushes back a string containing the type. The output could be:
For any object introduced by a WarpScript extension whose output of TYPEOF is not in the list thereof, the output would be preceded by "X-".
Note: since revision 2.5.0, the TYPEOF output of bucketizers, mappers, reducers is changed from 'MAPPER' to 'AGGREGATOR'.