DartDart_StreamingWriteCallbackFunction typedef
        DartDart_StreamingWriteCallbackFunction =
     void Function(Pointer<Void>  callback_data, Pointer<Uint8>  buffer, int size)
    
    
    
Implementation
typedef DartDart_StreamingWriteCallbackFunction = void Function(
    ffi.Pointer<ffi.Void> callback_data,
    ffi.Pointer<ffi.Uint8> buffer,
    int size);