encoding.py 文件源码

def is_protected_type(obj):
    """Determine if the object instance is of a protected type.

    Objects of protected types are preserved as-is when passed to
    force_unicode(strings_only=True).
    """
    return isinstance(obj, (
        types.NoneType,
        int, long,
        datetime.datetime, datetime.date, datetime.time,
        float, Decimal)
    )