Function get_time_bar_start 

pub fn get_time_bar_start(
    now: Timestamp,
    bar_type: &BarType,
    time_bars_origin: Option<SignedDuration>,
) -> Timestamp

Returns the time bar start as a timezone-aware Timestamp.

Panics

Panics if computing the base civil date or datetime from now fails, if step cannot be represented for the calendar arithmetic, or if the aggregation type is unsupported.