Fix for another 'no visible binding' NOTE.
Fix for another 'no visible binding' NOTE.

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