def isNull(text):
    """
    Test if a string 'looks' like a null value.
    This is useful for querying the API against a null key.

    Args:
        text: Input text

    Returns:
        True if the text looks like a null value
    """

    return str(text).strip().lower() in ['top', 'null', 'none', 'empty', 'false', '-1', '']