In the standard Python documentation, system calls appear as bold, fixed-width font. You can see this in the asyncore section, when it mentions select()
or poll()
for example:
http://docs.python.org/py3k/library/asyncore.html
I checked the source code for asyncore, and it has no special markups for these functions, so I'm not sure how one convinces Sphinx to do this. Is there a simple directive I can add to index.rst to make this work like I want?