def exists?(id, body)
      DirItems.new(@dir).fetch.each do |f|
        next unless f.start_with?("#{id}-")
        return true if safe_read(File.join(@dir, f)) == body
      end
      false
    end
def exists?(id, body)
      DirItems.new(@dir).fetch.each do |f|
        next unless f.start_with?("#{id}-")
        return true if safe_read(File.join(@dir, f)) == body
      end
      false
    end
Returns TRUE if a file for this wallet is already in the queue.