func (s *Session) Get(key interface{}) interface{} {
	if v, ok := s.Values[key]; ok {
		return v
	} else {
		return nil
	}
}
get value by key, nil if key not exist
package session
import ()
type Session struct {
	Values map[interface{}]interface{}
	MaxAge int
	id    string
	store Store
}
func (s *Session) ID() string {
	return s.id
}
func (s *Session) Set(key interface{}, value interface{}) error {
	s.Values[key] = value
	return nil
}