Show extant locks and unlocks.

def list_locks(account_id, resource_type=None, resource_id=None):
    """Show extant locks and unlocks.
    """
    locks = Client(BASE_URL, account_id).list_locks().json()

    for r in locks:
        if 'LockDate' in r:
            r['LockDate'] = datetime.fromtimestamp(r['LockDate'])
        if 'RevisionDate' in r:
            r['RevisionDate'] = datetime.fromtimestamp(r['RevisionDate'])

    print(tabulate.tabulate(
        locks,
        headers="keys",
        tablefmt='fancy_grid'))