# File lib/aws/record/validator.rb, line 220
      def ensure_at_least_one *keys
        found = keys.select{|k| options.has_key?(k) }
        unless found.count >= 1
          opts = keys.collect{|k| ":#{k}" }.join(', ')
          msg = "must provide at least one of the following options: #{opts}"
          raise ArgumentError, msg
        end
      end