def METHOD_NAME(table: catalog.Table, countries_regions: catalog.Table) -> catalog.Table:
    """Process net flows data, including country harmonization.
    Parameters
    ----------
    table : catalog.Table
        Table from the meadow dataset on net flows.
    countries_regions : catalog.Table
        Table from the owid countries-regions dataset.
    Returns
    -------
    table: catalog.Table
        Processed table.
    """
    df = pd.DataFrame(table).reset_index()
    # Create dictionary mapping country codes to harmonized country names.
    country_code_to_name = countries_regions[["name"]].to_dict()["name"]
    # Add Kosovo, which is missing in countries-regions.
    if "XKX" not in country_code_to_name:
        country_code_to_name["XKX"] = "Kosovo"
    columns = {
        "source_country_code": "source_country",
        "target_country_code": "target_country",
        "year": "year",
        "net_flow_twh": "net_flow__twh",
    }
    df = df[list(columns)].rename(columns=columns)
    # Change country codes to harmonized country names in both columns.
    for column in ["source_country", "target_country"]:
        df[column] = dataframes.map_series(
            series=df[column],
            mapping=country_code_to_name,
            warn_on_missing_mappings=True,
            show_full_warning=True,
        )
    table = (
        catalog.Table(df).set_index(["source_country", "target_country", "year"], verify_integrity=True).sort_index()
    )
    return table