How to use the webencodings.Encoding function in webencodings

def to_json():
    def numeric(t):
        return [
            t.representation, t.value,
            'integer' if t.int_value is not None else 'number']
    return {
        type(None): lambda _: None,
        str: lambda s: s,
        int: lambda s: s,
        list: lambda l: [to_json(el) for el in l],
        tuple: lambda l: [to_json(el) for el in l],
        Encoding: lambda e: e.name,
        ParseError: lambda e: ['error', e.kind],

        Comment: lambda t: '/* … */',
        WhitespaceToken: lambda t: ' ',
        LiteralToken: lambda t: t.value,
        IdentToken: lambda t: ['ident', t.value],
        AtKeywordToken: lambda t: ['at-keyword', t.value],
        HashToken: lambda t: ['hash', t.value,
                              'id' if t.is_identifier else 'unrestricted'],
        StringToken: lambda t: ['string', t.value],
        URLToken: lambda t: ['url', t.value],
        NumberToken: lambda t: ['number'] + numeric(t),
        PercentageToken: lambda t: ['percentage'] + numeric(t),
        DimensionToken: lambda t: ['dimension'] + numeric(t) + [t.unit],
        UnicodeRangeToken: lambda t: ['unicode-range', t.start, t.end],