src/vs/editor/common/model/prefixSumComputer.ts/ConstantTimePrefixSumComputer/constructor
class ConstantTimePrefixSumComputer:	constructor(values: number[]) {
		this._values = values;
		this._isValid = false;
		this._validEndIndex = -1;
		this._prefixSum = [];
		this._indexBySum = [];
	}