void DocumentSourceLookUp::reattachToOperationContext(OperationContext* opCtx) {
    if (_pipeline) {
        // We have a pipeline we're going to be executing across multiple calls to getNext(), so we
        // use Pipeline::reattachToOperationContext() to take care of updating '_fromExpCtx->opCtx'.
        _pipeline->reattachToOperationContext(opCtx);
        invariant(_fromExpCtx->opCtx == opCtx);
    } else if (_fromExpCtx) {
        _fromExpCtx->opCtx = opCtx;
    }
}
void DocumentSourceLookUp::reattachToOperationContext(OperationContext* opCtx) {
    if (_pipeline) {
         
         
        _pipeline->reattachToOperationContext(opCtx);
        invariant(_fromExpCtx->opCtx == opCtx);
    } else if (_fromExpCtx) {
        _fromExpCtx->opCtx = opCtx;
    }
}