public static void connectLeadLagFunctionsToPartition(LeadLagInfo leadLagInfo,
      PTFPartitionIterator<Object> pItr) throws HiveException {
    if (leadLagInfo == null || leadLagInfo.getLeadLagExprs() == null) {
      return;
    }

    for (ExprNodeGenericFuncDesc llFnDesc : leadLagInfo.getLeadLagExprs()) {
      GenericUDFLeadLag llFn = (GenericUDFLeadLag) llFnDesc.getGenericUDF();
      llFn.setpItr(pItr);
    }
  }
@return the name of the operator
ql/src/java/org/apache/hadoop/hive/ql/exec/PTFOperator.java