[Soot-list] What does this method return?

[Peng Gao]

Hi,

I am reading the soot source code and got confused with the following 
method 'simpleSources' in 'soot.jimple.spark.pag.PAG.java'.

This method should return a set, but I am just wondering what are the
elements inside this set?

Thanks a lot in advance.

Cheers

-Gao Peng