def coerce_to_str(obj):
    """
    Coerce a constant VBA object (integer, Null, etc) to a string.
    :param obj: VBA object
    :return: string
    """
    # in VBA, Null/None is equivalent to an empty string
    if ((obj is None) or (obj == "NULL")):
        return ''
    else:
        return str(obj)