anchor.diff:  
   populate_edges(MapGraph, _, _, []) ->
   	MapGraph;
  -populate_edges(MapGraph, Dims, Vertex, [Neighbor|Neighbors]) ->
  +populate_edges(MapGraph, #{height := Height, width := Width} = Dims, Vertex, [Neighbor|Neighbors]) ->
   	NeighborRow = maps:get(row, Neighbor),
   	NeighborCol = maps:get(col, Neighbor),
  -	case NeighborRow > 0 andalso NeighborCol > 0 of
  -		false ->
  -			ok;
  +	case NeighborRow > 0 andalso NeighborCol > 0 andalso 
  +			 NeighborRow < Height andalso NeighborCol < Width of
   		true ->
   			case digraph:vertex(MapGraph, Neighbor) of
   				false ->
  
positive.code: 						true ->
  							ok
  					end
  			end
  	end,
  	populate_edges(MapGraph, Dims, Vertex, Neighbors).
  
  
negative.code: 				 	Vertex#{row := Row - 1},
  					Vertex#{col := Col + 1},
  					Vertex#{row := Row + 1},
  					Vertex#{col := Col - 1}
  			 	],
  	case digraph:vertex(MapGraph, Vertex) of
  		false ->
  