Opening time (ISO 8601) of last candle, i.e. "2020-04-28T23:00:00.000Z"
Desired time slice in seconds.
Opening time (ISO 8601) of first candle, i.e. "2020-04-28T00:00:00.000Z"
Opening time (ISO 8601) of last candle, i.e. "2020-04-28T23:00:00.000Z"