# File lib/redis.rb, line 1346
  def zadd(key, *args)
    synchronize do |client|
      if args.size == 1 && args[0].is_a?(Array)
        # Variadic: return integer
        client.call([:zadd, key] + args[0])
      elsif args.size == 2
        # Single pair: return boolean
        client.call([:zadd, key, args[0], args[1]], &_boolify)
      else
        raise ArgumentError, "wrong number of arguments"
      end
    end
  end