def _lowercase(dictin):
    """
    Make all keys from a dictionary lowercase.
    Args:
        dictin (dict): dictionary
    Returns:
        modified dictionary dictin
    Ok for nested dictionaries, but will not work for dictionaries within lists.
    """
    if isinstance(dictin, dict):
        return {k.lower(): _lowercase(v) for k, v in dictin.items()}
    else:
        return dictin