func (l LabelSet) MergeFromMetric(m Metric) {
	for k, v := range m {
		l[k] = v
	}
}
MergeFromMetric merges Metric into this LabelSet.
package model
import (
	"fmt"
	"sort"
	"strings"
)
type LabelSet map[LabelName]LabelValue
func (l LabelSet) Merge(other LabelSet) LabelSet {
	result := make(LabelSet, len(l))
	for k, v := range l {
		result[k] = v
	}
	for k, v := range other {
		result[k] = v
	}
	return result
}
func (l LabelSet) String() string {
	labelStrings := make([]string, 0, len(l))
	for label, value := range l {
		labelStrings = append(labelStrings, fmt.Sprintf("%s=%q", label, value))
	}
	switch len(labelStrings) {
	case 0:
		return ""
	default:
		sort.Strings(labelStrings)
		return fmt.Sprintf("{%s}", strings.Join(labelStrings, ", "))
	}
}