"""
Fetchers retrieve remote data and return it in a format suitable for further processing, they also return its version, which should be considered opaque, though it is usually a checksum.
"""

import sqlite3
from typing import Tuple
import pandas as pd
from .metadata import Metadata

def fetch_onet_database(meta: Metadata) -> Tuple[sqlite3.Connection, str]:
    raise NotImplementedError

def fetch_oesm_data(meta: Metadata) -> Tuple[pd.DataFrame, str]:
    raise NotImplementedError

def fetch_epoch_remote_data(meta: Metadata) -> Tuple[pd.DataFrame, str]:
    raise NotImplementedError