nl_tokens: Counts the number of leading required arguments .
pl_tokens: function ( expected , expectedIndex , value ) { var i = expectedIndex - 1 ; var matchingRequires = 0 while ( i >= 0 ) { if ( ! isOptionalType ( expected [ i ] ) && isOfType ( <mask> , expected [ i ] ) ) { matchingRequires ++ ; } i -- ; } return matchingRequires ; }