def METHOD_NAME(indigo: Indigo, filename: str):
    """
    Provide proper Indigo iterator depending on file format
    """
    extension = path.splitext(filename)[1]
    iterator = {
        ".sdf": indigo.iterateSDFile,
        ".smi": indigo.iterateSmilesFile,
        ".sma": indigo.iterateSmilesFile,
        ".smiles": indigo.iterateSmilesFile,
        ".rdf": indigo.iterateRDFile,
    }.get(extension)
    return iterator(filename)