Return an iterable object containing all entries stored in the specified
    bank.

def ls(bank):
    '''
    Return an iterable object containing all entries stored in the specified
    bank.
    '''
    _init_client()
    query = "SELECT etcd_key FROM {0} WHERE bank='{1}'".format(
        _table_name, bank)
    cur, _ = run_query(client, query)
    out = [row[0] for row in cur.fetchall()]
    cur.close()
    return out