def add!(timings)
      timings.descriptions.each{|d|
        add_cpu_time(d, timings.cpu_time(d))
        add_wall_time(d, timings.wall_time(d))
      }
    end
def add!(timings)
      timings.descriptions.each{|d|
        add_cpu_time(d, timings.cpu_time(d))
        add_wall_time(d, timings.wall_time(d))
      }
    end
Add another timings object to this one