def _generate_unique_agency_id(df, col_name):
    """
    Generate unique agency id

    Parameters
    ----------
    df : pandas:DataFrame
    col_name : str
        typically will be 'agency_name'

    Returns
    -------
    col_snake_no_amps : str
    """
    col = df[col_name].astype(str)
    col_snake_case = col.str.replace('\\s+', '_')
    col_snake_no_amps = col_snake_case.str.replace('&', 'and')
    return col_snake_no_amps.str.lower()
