f := zone.creep.timestep()
zone.creep.timestep() := f

Get/set the timestep used by the zone creep module when it is active. This may not be the timestep used, as other active modules may require a smaller timestep.

Returns:f - the current zone creep module timestep
Accepts:f - sets the current zone creep module timestep. This does not change any active automatic timestep calculations that may be active.