# File lib/aws/core/async_handle.rb, line 69
      def on_complete(&block)
        if !@_async_status.nil?
          block.call(@_async_status)
        else
          (@_async_callbacks ||= []) << {
            :failure => lambda { block.call(:failure) },
            :success => lambda { block.call(:success) }
          }
        end
      end