stoch(src, high, low, len, _id) {
        let id = this._tsid(_id, `sum(${len})`)
        let x = 100 * (src[0] - this.lowest(low, len)[0])
        let y = this.highest(high, len)[0] - this.lowest(low, len)[0]
        return this.ts(x / y, id, src.__tf__)
    }
Stochastic
@param {TS} src - Input
@param {TS} high - TS of high
@param {TS} low - TS of low
@param {number} len - Length
@return {TS} - New time-series