Groovier way of getting sum from a nested property

Question

What's the groovier way to do this?

def totalSightings=0;
year.months.each{month->
    month.weeks.each{week->
        week.days.each{day->
           total+=day.sightings;
        }
    }
}

Answer 1

year.months​.weeks​.days​.sightings.flatten().sum()