attrs.go
func (a *Attrs) MergeAttrs(attrs *Attrs) {
	if attrs == nil {
		return
	}
	a.attrsLock.Lock()
	defer a.attrsLock.Unlock()
	for hash, val := range attrs.attrs {
		a.attrs[hash] = val
	}
}
func (a *Attrs) MergeAttrs(attrs *Attrs) {
	if attrs == nil {
		return
	}
	a.attrsLock.Lock()
	defer a.attrsLock.Unlock()
	for hash, val := range attrs.attrs {
		a.attrs[hash] = val
	}
}
// MergeAttrs accepts another existing Attrs and merges the attributes into its own.