private Set<String> getFunctionOutputs(List<String> colNames, List<ExprNodeDesc> targets) {
      Set<String> functionOutputs = new HashSet<String>();
      for (int i = 0; i < targets.size(); i++) {
        if (targets.get(i) instanceof ExprNodeGenericFuncDesc) {
          functionOutputs.add(colNames.get(i));
        }
      }
      return functionOutputs;
    }
merges SEL-SEL or FIL-FIL into single operator
ql/src/java/org/apache/hadoop/hive/ql/optimizer/NonBlockingOpDeDupProc.java