async def METHOD_NAME(cls, ctx, argument):
    """Converter for a Source being used as a type annotation"""
    cog = ctx.bot.get_cog('News')
    chosen_source = None
    for enabled_source in cog.sources.values():
        if argument in enabled_source.aliases:
            chosen_source = enabled_source
            break
    if chosen_source is None:
        raise BadArgument(f"No source under the name `{argument}` found.")
    return chosen_source