# File lib/aws/ec2/route_table/association.rb, line 74
        def initialize route_table, association_id, subnet_id
          @route_table = route_table
          @association_id = association_id
          if subnet_id
            @main = false
            @subnet = Subnet.new(subnet_id,
              :config => route_table.config)
          else
            @main = true
          end
        end