Remove unused variable.
Remove unused variable.

mbostock/stack,bondah/GIS_Intro,Archie22is/stack,fbukevin/weic_d3js,ee08b397/stack,Archie22is/stack,banj/stack,SoxFace/stack,SoxFace/stack,mbostock/stack,ImFreeApp/resource-stack,fbukevin/weic_d3js,bondah/GIS_Intro,ImFreeApp/resource-stack,ee08b397/stack,banj/stack