Possibly missing uniq operator in 13.12


We are using 13.12 for our development.
Whenever I try to use uniq operator it gives the following error, though the documentation states the addition of uniq operator in 13.12.
Am I doing something wrong?

AFL% uniq();
SystemException in file: src/query/OperatorLibrary.cpp function: createLogicalOperator line: 85
Error description: Query processor error. Logical operator ‘uniq’ does not exist.
Failed query id: 1100940384067