# File lib/calendar_grid.rb, line 70
    def build(&day_plugin)
      m = months
      m.each do |month|
        first = grid_start(month.date)
        last = increment_month(month.date, 1) - 1.day
        step_days(first, last, 7) do |time|
          month.weeks << days_for_a_week(month.date, time, &day_plugin)
        end
      end 
      years = partition_years m
      Calendar.new years
    end