You are an expert in writing code in many different languages. Your goal is to perform code completion for the following code, keeping in mind the rest of the code and the file meta data.
    Metadata details:
    filename: weightdevice.go
    path of file: ./repos/docker-ce/components/cli/opts
    
    the code of the file until where you have to start completion: package opts

import (
	"fmt"
	"strconv"
	"strings"

	"github.com/docker/docker/api/types/blkiodev"
)

// ValidatorWeightFctType defines a validator function that returns a validated struct an
    
func (opt *WeightdeviceOpt) Set(val string) error {
	var value *blkiodev.WeightDevice
	if opt.validator != nil {
		v, err := opt.validator(val)
		if err != nil {
			return err
		}
		value = v
	}
	(opt.values) = append((opt.values), value)
	return nil
}