You are an expert in writing code in many different languages. Your goal is to perform code completion for the following code, keeping in mind the rest of the code and the file meta data.
    Metadata details:
    filename: level3.go
    path of file: ./repos/mylg/lg
    
    the code of the file until where you have to start completion: // Package lg provides looking glass methods for selected looking glasses
// Level3 Carrier Looking
    
func (p *Level3) GetNodes() []string {
	// Memory cache
	if len(p.Nodes) > 1 {
		return p.Nodes
	}
	level3Nodes = p.FetchNodes()
	var nodes []string
	for node := range level3Nodes {
		nodes = append(nodes, node)
	}
	sort.Strings(nodes)
	p.Nodes = nodes
	return nodes
}