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: index.go
    path of file: ./repos/arduino-cli/internal/arduino/cores/packageindex
    
    the code of the file until where you have to start completion: // This file is part of arduino-cli.
//
// Copyright 2020 ARDUINO SA (http://www.arduino.cc/)
//
// This software is released under the GNU General Public License version 3,
// which covers the main part of arduino-cli.
// The terms
    
func LoadIndex(jsonIndexFile *paths.Path) (*Index, error) {
	buff, err := jsonIndexFile.ReadFile()
	if err != nil {
		return nil, err
	}
	var index Index
	err = easyjson.Unmarshal(buff, &index)
	if err != nil {
		return nil, err
	}

	jsonSignatureFile := jsonIndexFile.Parent().Join(jsonIndexFile.Base() + ".sig")
	if jsonSignatureFile.Exist() {
		trusted, _, err := security.VerifyArduinoDetachedSignature(jsonIndexFile, jsonSignatureFile)
		if err != nil {
			logrus.
				WithField("index", jsonIndexFile).
				WithField("signatureFile", jsonSignatureFile).
				WithError(err).Warnf("Checking signature")
		} else {
			logrus.
				WithField("index", jsonIndexFile).
				WithField("signatureFile", jsonSignatureFile).
				WithField("trusted", trusted).Infof("Checking signature")
			index.IsTrusted = trusted
		}
	} else {
		logrus.WithField("index", jsonIndexFile).Infof("Missing signature file")
	}

	if jsonIndexFile.Base() == "installed.json" {
		index.isInstalledJSON = true
	}

	return &index, nil
}