fcn colorGraph(nodeStr){	// "0-1 1-2 2-0 3"
   numEdges,graph := 0,Dictionary();  // ( 0:(1,2), 1:L(0,2), 2:(1,0), 3:() )
   foreach n in (nodeStr.split(" ")){ // parse string to graph
      n=n - " ";
      if(n.holds("-")){
	 a,b := n.split("-");	// keep as string
	 graph.appendV(a,b); graph.appendV(b,a);
	 numEdges+=1;
      }
      else graph[n]=T;		// island
   }
   colors,colorPool := Dictionary(), ["A".."Z"].walk();
   graph.pump(Void,'wrap([(node,nbrs)]){  // ( "1",(0,2), "3",() )
      clrs:=colorPool.copy();	// all colors are available, then remove neighbours
      foreach i in (nbrs){ clrs.remove(colors.find(i)) }  // if nbr has color, color not available
      colors[node] = clrs[0];	// first available remaining color
   });
   return(graph,colors,numEdges)
}