nl_tokens: Perform a set difference A - B by subtracting all items in array B from array A .
pl_tokens: function ( arrayA , arrayB ) { var clone = slice . <mask> ( arrayA ) , ln = clone . length , i , j , lnB ; for ( i = 0 , lnB = arrayB . length ; i < lnB ; i ++ ) { for ( j = 0 ; j < ln ; j ++ ) { if ( clone [ j ] === arrayB [ i ] ) { erase ( clone , j , 1 ) ; j -- ; ln -- ; } } } return clone ; }