Format possibly compound value given the FieldInfo

def format_value(field_info, value, section):
    """Format possibly compound value given the FieldInfo"""
    if section == "FORMAT" and field_info.id == "FT":
        if not value:
            return "."
        elif isinstance(value, list):
            return ";".join(map(format_atomic, value))
    elif field_info.number == 1:
        if value is None:
            return "."
        else:
            return format_atomic(value)
    else:
        if not value:
            return "."
        else:
            return ",".join(map(format_atomic, value))