function isBoundary(i, dir, any) {
        if (any) { return isEmpty(i) != isEmpty(i + dir); }
        return !isEmpty(i) && isEmpty(i + dir);
      }
function isBoundary(i, dir, any) {
        if (any) { return isEmpty(i) != isEmpty(i + dir); }
        return !isEmpty(i) && isEmpty(i + dir);
      }
function isBoundary ( i , dir , any ) { if ( any ) { return isEmpty ( i ) != isEmpty ( i + dir ) ; } return ! isEmpty ( i ) && isEmpty ( i + dir ) ; }
ace_patch
ace_patch
Check if an index is boundary