func NewMeta() Meta {
	return make(map[string][]string)
}
NewMeta initializes Meta's underlying map
package task
import (
	"context"
	"fmt"
	"net/url"
)
type NewWorker func(info string) Worker
type Worker interface {
	DoTask(context.Context) (Result, string)
}
type meta interface {
	SetMeta(key string, value ...string)
	GetMeta() url.Values
}
type Meta map[string][]string
func (m Meta) SetMeta(key string, value ...string) {
	m[key] = value
}
func (m Meta) GetMeta() url.Values { return url.Values(m) }