kcw(src, len, mult, use_tr = true, _id, _tf) {
        let id = this._tsid(_id, `kcw(${len},${mult},${use_tr})`)
        let kc = this.kc(src, len, mult, use_tr, `kcw`, _tf)
        return this.ts((kc[1][0] - kc[2][0]) / kc[0][0], id, src.__tf__)
    }
Keltner Channels Width
@param {TS} src - Input
@param {number} len - Length
@param {number} mult - Multiplier
@param {boolean} [use_tr] - Use true range
@return {TS} - New time-series