For use by packages that mimic/divert auto printing e.g. IRkernel and knitr
Not for use by users. Exported only for use by IRkernel (Jupyter) and knitr.
Should IRkernel/Jupyter print a data.table returned invisibly by DT[,:=] ? This is a read-once function since it resets an internal flag. If you need the value more than once in your logic, store the value from the first call.
TRUE or FALSE.