inZone method
Constructs a ZonedClock from a clock (the target of the method), a time zone, and a calendar system.
clock: Clock to use in the returned object.zone: Time zone to use in the returned object.calendar: Calendar to use in the returned object.
Returns: A ZonedClock with the given clock, time zone and calendar system.
Implementation
ZonedClock inZone(DateTimeZone zone, [CalendarSystem? calendar]) =>
ZonedClock(this, zone, calendar ?? CalendarSystem.iso);