func NewGroup(new func() interface{}) *Group {
	if new == nil {
		panic("container.group: can't assign a nil to the new function")
	}
	return &Group{
		new: new,
	}
}
NewGroup news a group container.
package group
import "sync"
type Group struct {
	new  func() interface{}
	objs sync.Map
	sync.RWMutex
}