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: env_minio.go
    path of file: ./repos/gotosocial/vendor/github.com/minio/minio-go/v7/pkg/credentials
    
    the code of the file until where you have to start completion: /*
 * MinIO Go Library for Amazon S3 Compatible Cloud Storage
 * Copyright 2017 MinIO, Inc.
 *
 * License
    
func (e *EnvMinio) Retrieve() (Value, error) {
	e.retrieved = false

	id := os.Getenv("MINIO_ROOT_USER")
	secret := os.Getenv("MINIO_ROOT_PASSWORD")

	signerType := SignatureV4
	if id == "" || secret == "" {
		id = os.Getenv("MINIO_ACCESS_KEY")
		secret = os.Getenv("MINIO_SECRET_KEY")
		if id == "" || secret == "" {
			signerType = SignatureAnonymous
		}
	}

	e.retrieved = true
	return Value{
		AccessKeyID:     id,
		SecretAccessKey: secret,
		SignerType:      signerType,
	}, nil
}