def _split_string(value, sep=','):
    """Safe split a string removing empty/falsey strings resulting from
    the split.

    Returns
    -------
    list or None
        List of values produced by a string split, otherwise None if a falsey
        value is passed in.
    """

    if value:
        return [v.strip() for v in value.split(sep) if v.strip()]
    else:
        return None