def METHOD_NAME(buildid, artifact_name, url_prefix, access_token):
    """get download url"""
    artifact_req = Request("https://dev.azure.com/{}/_apis/build/builds/{}/artifacts?artifactName={}&api-version=5.0"
                           .format(url_prefix, buildid, artifact_name))
    # If access token is not empty, set headers
    if access_token:
        artifact_req.add_header('Authorization',
                                'Basic {}'.format(base64.b64encode(access_token.encode('utf-8')).decode('utf-8')))
    resp = urlopen(artifact_req)
    j = json.loads(resp.read().decode('utf-8'))
    download_url = j['resource']['downloadUrl']
    artifact_size = int(j['resource']['properties']['artifactsize'])
    return (download_url, artifact_size)