Added example for naming by, completes #514.
Added example for naming by, completes #514.

Rdatatable/data.table,Rdatatable/data.table,vlulla/data.table,vlulla/data.table,Rdatatable/data.table,vlulla/data.table,jangorecki/data.table,Rdatatable/data.table,jangorecki/data.table,jangorecki/data.table,vlulla/data.table,jangorecki/data.table