xcffib is intended to be a (mostly) drop-in replacement for xpyb. 
xpyb has an inactive upstream, several memory leaks, is python2 
only and doesn't have pypy support. xcffib is a binding which 
uses cffi, which mitigates some of the issues described above. 
xcffib also builds bindings for 27 of the 29 (xprint and xkb are 
missing) X extensions in 1.10.
