Python 3 fixes to change directory command. Add some comments too.
Python 3 fixes to change directory command. Add some comments too.

wasade/networkx,jakevdp/networkx,sharifulgeo/networkx,kernc/networkx,dmoliveira/networkx,dmoliveira/networkx,yashu-seth/networkx,jfinkels/networkx,nathania/networkx,RMKD/networkx,debsankha/networkx,jcurbelo/networkx,farhaanbukhsh/networkx,jakevdp/networkx,cmtm/networkx,kernc/networkx,jni/networkx,ionanrozenfeld/networkx,blublud/networkx,harlowja/networkx,aureooms/networkx,tmilicic/networkx,michaelpacer/networkx,ionanrozenfeld/networkx,harlowja/networkx,jakevdp/networkx,chrisnatali/networkx,kernc/networkx,dhimmel/networkx,farhaanbukhsh/networkx,bzero/networkx,ghdk/networkx,goulu/networkx,chrisnatali/networkx,bzero/networkx,sharifulgeo/networkx,farhaanbukhsh/networkx,harlowja/networkx,aureooms/networkx,beni55/networkx,nathania/networkx,ltiao/networkx,andnovar/networkx,bzero/networkx,NvanAdrichem/networkx,aureooms/networkx,ionanrozenfeld/networkx,nathania/networkx,blublud/networkx,dhimmel/networkx,ghdk/networkx,jni/networkx,jni/networkx,chrisnatali/networkx,OrkoHunter/networkx,blublud/networkx,RMKD/networkx,debsankha/networkx,JamesClough/networkx,SanketDG/networkx,Sixshaman/networkx,sharifulgeo/networkx,dhimmel/networkx,RMKD/networkx,dmoliveira/networkx,debsankha/networkx,ghdk/networkx