class Redis

def _scan(command, cursor, args, options = {}, &block)
  # SSCAN/ZSCAN/HSCAN already prepend the key to +args+.
  args << cursor
  if match = options[:match]
    args.concat(["MATCH", match])
  end
  if count = options[:count]
    args.concat(["COUNT", count])
  end
  synchronize do |client|
    client.call([command] + args, &block)
  end
end