TYPEMAP
decode_ctx*     T_PTROBJ_DECODER
seqdecode_ctx*  T_PTROBJ_SEQDECODER

INPUT
T_PTROBJ_DECODER
    if (sv_derived_from($arg, \"CBOR::Free::Decoder\")) {
        IV tmp = SvIV((SV*)SvRV($arg));
        $var = INT2PTR($type, tmp);
    }
    else
        croak(\"$var is not of type CBOR::Free::Decoder\")
T_PTROBJ_SEQDECODER
    if (sv_derived_from($arg, \"CBOR::Free::SequenceDecoder\")) {
        IV tmp = SvIV((SV*)SvRV($arg));
        $var = INT2PTR($type, tmp);
    }
    else
        croak(\"$var is not of type CBOR::Free::SequenceDecoder\")