/*backtest
start: 2019-01-22 00:00:00
end: 2019-01-23 00:00:00
period: 30m
exchanges: [{"eid":"OKCoin_EN","currency":"BTC_USD"}]
*/

void main() {
    json cfgA = R"({
        "extension" : {
            "layout" : "single", 
            "height" : 300,