def csv_safe(value):
    """Remove any beginning character '=-+@' from string value.
    Change None to empty string.
    See http://georgemauer.net/2017/10/07/csv-injection.html
    """
    if isinstance(value, str):
        while len(value) and value[0] in '=-+@':
            value = value[1:]
    elif value is None:
        value = ''
    return value