highlight breakpoints with pdb?

[Xin Jin]

I use pdb with gud to debug python scripts. I am just wondering if there is way 
to highlight the lines with breakpoints? For example, in some screenshots of 
gud-gdb, some people seem to have red circles to the left of lines with 
breakpoints. How to achieve that with pdb? And is there a way to list all 
breakpoints (like the breakpoints buffer of gud-gdb)?

I actually tried realgud once, and it did have this feature. However, realgud 
is lacking documentation, and I find it extremely confusing to use. I have very 
limited knowledge of elisp, so I cannot figure out what is going on without a 
more detailed guide.

Thanks.