    # File lib/active_support/time_with_zone.rb, line 216
        def since(other)
          # If we're adding a Duration of variable length (i.e., years, months, days), move forward from #time,
          # otherwise move forward from #utc, for accuracy when moving across DST boundaries
          if duration_of_variable_length?(other)
            method_missing(:since, other)
          else
            utc.since(other).in_time_zone(time_zone)
          end
        end