[Discuss-gnuradio] Any example to show me how to use the " QAM Demod " module?

Hi， ALL

Are there any good examples or documents to teach me how to use the " QAM Demod " module?

I confused about the output data format of the QAM Demod module and how to deal with them. 

And why QAM demod do not output a complex data?

I also found the description of the "QAM Demod" block is the same as "QAM Mod" module.

Any documents tell us how the QAM demod works?

Thanks very much!