Mode = function() {
    this.$tokenizer = new Tokenizer(new TextHighlightRules().getRules());
    this.$behaviour = new Behaviour();
}
Range.clipRows(firstRow, lastRow) -> Range
- firstRow (Number): The starting row
- lastRow (Number): The ending row

Returns the part of the current `Range` that occurs within the boundaries of `firstRow` and `lastRow` as a new `Range` object.