def parse_arn(arn):
    # http://docs.aws.amazon.com/general/latest/gr/aws-arns-and-namespaces.html
    elements = arn.split(':')
    result = {'arn': elements[0],
            'partition': elements[1],
            'service': elements[2],
            'region': elements[3],
            'account': elements[4]
           }
    if len(elements) == 7:
        result['resourcetype'], result['resource'] = elements[5:]
    elif '/' not in elements[5]:
        result['resource'] = elements[5]
        result['resourcetype'] = None
    else:
        result['resourcetype'], result['resource'] = elements[5].split('/')
    return result