src/vs/editor/common/model/prefixSumComputer.ts/PrefixSumComputer/setValue
class PrefixSumComputer:	public setValue(index: number, value: number): boolean {
		index = toUint32(index);
		value = toUint32(value);

		if (this.values[index] === value) {
			return false;
		}
		this.values[index] = value;
		if (index - 1 < this.prefixSumValidIndex[0]) {
			this.prefixSumValidIndex[0] = index - 1;
		}
		return true;
	}