__init__.py 文件源码

def to_unicode(source, encoding="utf-8", param="value"):
    """Helper to normalize input to unicode.

    :arg source:
        source bytes/unicode to process.

    :arg encoding:
        encoding to use when decoding bytes instances.

    :param param:
        optional name of variable/noun to reference when raising errors.

    :raises TypeError: if source is not unicode or bytes.

    :returns:
        * returns unicode strings unchanged.
        * returns bytes strings decoded using *encoding*
    """
    assert encoding
    if isinstance(source, unicode):
        return source
    elif isinstance(source, bytes):
        return source.decode(encoding)
    else:
        raise ExpectedStringError(source, param)