try
fun tryHoldZoneFor(holder: ZoneHolderIfc, zone: Zone, duration: Double, action: ZoneHoldActionIfc): ZoneRequest?(source)
Takes one zone for a stated duration unless it is already promised, in which case: null.
tryHoldZonesFor with one zone. The duration runs from the instant the hold begins, exactly as in holdZoneFor, so a zone that takes a while to drain is still held for its full term.
Return
the request, or null when the zone is already promised to another holder
Parameters
holder
who is taking the space
zone
the zone to take, which must be on this guide path
duration
how long to hold it once the hold begins, strictly positive
action
told when the hold begins and when the clock gives it back