human
I wrote the below code

    def b64_decode_meta(crypto_meta):
        return {str(name): (base64.b64decode(val) if (name in ('iv', 'key')) else (b64_decode_meta(val) if isinstance(val, dict) else (val.encode('utf8') if six.PY2 else val))) for (name, val) in crypto_meta.items()}
    try:
        if (not isinstance(value, six.string_types)):
            raise ValueError('crypto    meta    not    a    string')
        val = json.loads(urlparse.unquote_plus(value))
        if (not isinstance(val, collections.Mapping)):
            raise ValueError('crypto    meta    not    a    Mapping')
        return b64_decode_meta(val)
    except (KeyError, ValueError, TypeError) as err:
        msg = ('Bad    crypto    meta    %r:    %s' % (value, err))
        raise EncryptionException(msg)

What's a good function header?
assistant
#Here's a good function header.

def load_crypto_meta(value):