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: ginkgo.go
    path of file: ./repos/ginkgo/ginkgo/outline
    
    the code of the file until where you have to start completion: package outline

import (
	"go/ast"
	"go/token"
	"strconv"

	"github.com/onsi/ginkgo/v2/types"
)

const (
	// undefine
    
func labelFromCallExpr(ce *ast.CallExpr) []string {

	labels := []string{}
	if len(ce.Args) < 2 {
		return labels
	}

	for _, arg := range ce.Args[1:] {
		switch expr := arg.(type) {
		case *ast.CallExpr:
			id, ok := expr.Fun.(*ast.Ident)
			if !ok {
				// to skip over cases where the expr.Fun. is actually *ast.SelectorExpr
				continue
			}
			if id.Name == "Label" {
				ls := extractLabels(expr)
				labels = append(labels, ls...)
			}
		}
	}
	return labels
}