Also you can provide packer and unpacker functions for any other type (even for user type defined via `Q_DECLARE_METATYPE`) or MsgPack type.
Thread-safety
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At this time it is not thread safe to call `MsgPack::registerPacker`, `MsgPack::registerUnpacker` and `MsgPack::setCompatibilityModeEnabled` from different threads.
pack and unpack methods do not use any global data, so