time series lastest record time by account.

def status(config):
    """time series lastest record time by account."""
    with open(config) as fh:
        config = yaml.safe_load(fh.read())
    jsonschema.validate(config, CONFIG_SCHEMA)
    last_index = get_incremental_starts(config, None)
    accounts = {}
    for (a, region), last in last_index.items():
        accounts.setdefault(a, {})[region] = last
    print(yaml.safe_dump(accounts, default_flow_style=False))