Add not_implemented_for multigraph check
Add not_implemented_for multigraph check

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